State v. Lebrick ( 2020 )


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    STATE OF CONNECTICUT v. HORVIL F. LEBRICK
    (SC 20083)
    Robinson, C. J., and Palmer, McDonald, D’Auria, Mullins and Ecker, Js.
    Syllabus
    Convicted of the crimes of felony murder, home invasion, conspiracy to
    commit home invasion, burglary in the first degree, attempt to commit
    robbery in the first degree, and assault in the first degree in connection
    with the shooting deaths of the victim and two of the defendant’s accom-
    plices, A and M, the defendant appealed to the Appellate Court, claiming,
    inter alia, that the trial court had violated his constitutional right to
    confrontation when it admitted into evidence the former testimony of
    a purportedly unavailable witness, P, and the testimony of the state’s
    expert witness, S, about ballistic evidence. Pursuant to a court order, P
    reluctantly testified at the defendant’s probable cause hearing. P testified
    that she had met with the defendant in Brooklyn, New York, on the day
    after the shootings in question and that the defendant confessed that
    he had gone to East Hartford with A and M intending to rob B, a drug
    dealer. According to P, the defendant stated that he had kicked open
    the door to B’s apartment and encountered the victim, who was armed
    with a gun. The defendant disarmed the victim and proceeded to another
    room of the apartment, from where he heard several gunshots and the
    shooter ask the victim how many people remained in the apartment. P
    further testified that the defendant had told her that he then used the
    gun he had taken from the victim to shoot his way out of the apartment
    and past the bodies of A and M, both of whom apparently had been
    shot. The state could not locate P before the defendant’s trial and sought
    to admit her former testimony from the probable cause hearing pursuant
    to the provision (§ 8-6 [1]) of the Connecticut Code of Evidence allowing
    for the admission at a subsequent trial of an unavailable witness’ prior
    testimony. The defendant moved to suppress P’s former testimony on
    the ground that the state had failed to establish P’s unavailability insofar
    as it had not made diligent and good faith efforts to procure her atten-
    dance at trial. The court held a hearing on the motion at which an
    inspector for the state’s attorney’s office, H, testified about his efforts
    to locate P. H testified that he first conducted electronic searches in
    the Hartford Police Department’s in-house computer database and the
    National Crime Information Center (NCIC) database, a national reposi-
    tory of criminal records, but that those searches yielded no results. He
    then used CLEAR, a subscription based search engine that aggregates
    publicly available data, which revealed two addresses for P and one
    address for P’s mother, all of which were in New York, as well as several
    phone numbers for P, none of which was in service or receiving calls.
    H forwarded the addresses to the Kings County District Attorney’s Office
    in Brooklyn, and an investigator in that office, G, was assigned to serve
    an interstate summons on P. Over two days, G visited one of P’s
    addresses on three occasions and P’s other address and her mother’s
    address one time each, but no one was home on any of those occasions.
    The trial court denied the defendant’s motion to suppress P’s former
    testimony, concluding that the state’s efforts to locate P were sufficient
    to establish her unavailability under both § 8-6 (1) of the Connecticut
    Code of Evidence and the confrontation clause of the federal constitu-
    tion. The defendant also moved to suppress S’s expert testimony about
    ballistic evidence, arguing that its admission would violate his right to
    confrontation because it was based on a ballistic report, which the
    defendant claimed contained testimonial hearsay, prepared by a former
    employee of the state forensic laboratory who had examined the ballistic
    evidence recovered from the crime scene but who was unavailable to
    testify because he died before the defendant’s trial. The trial court denied
    the defendant’s motion to suppress S’s testimony, agreeing with the
    state that there was no confrontation clause issue because S had formed
    his own independent conclusions after reviewing the former employee’s
    report and photographs, and the defendant could cross-examine S at
    trial. S ultimately testified, and the state emphasized during its closing
    argument that the ballistic evidence indicated that the bullet that killed
    the victim came from the gun used by the defendant. The Appellate
    Court affirmed the judgment of the trial court, concluding, inter alia,
    that the defendant’s right to confrontation was not violated by the admis-
    sion of P’s former testimony. On the granting of certification, the defen-
    dant appealed to this court. Held:
    1. The Appellate Court incorrectly concluded that the admission of P’s
    former testimony did not violate the defendant’s right to confrontation,
    the state having failed to establish that it undertook a reasonable, dili-
    gent, and good faith effort to procure P’s attendance at the defendant’s
    trial: this court, having concluded that the issue of whether a witness
    is unavailable for purposes of the confrontation clause presents a mixed
    question of law and fact subject to plenary review, employed four objec-
    tive criteria for determining the reasonableness of the state’s efforts to
    demonstrate the unavailability of a witness, including the importance
    of the witness to the state’s case, the seriousness of the crimes for
    which the defendant was tried, whether the witness had reason to favor
    the prosecution, and whether the state made the same sort of effort to
    procure the witness for trial that it would have made if it did not have
    the witness’ prior testimony available; in the present case, although the
    record did not reflect that P received any consideration for her testi-
    mony, such as an immunity arrangement, the other three criteria weighed
    in favor of the defendant because the defendant was charged with
    extremely serious crimes, P’s testimony was critical to the state’s case
    as she provided crucial, inculpatory testimony regarding the defendant’s
    role in the commission of the crimes that directly contradicted the
    defendant’s own statements about his version of the events and that
    was not provided by any other witness, namely, that the defendant had
    confessed that he had gone to the apartment intending to commit a
    robbery, he was armed with a gun that he had taken from the victim,
    and he had used that gun to shoot his way out of the apartment, and,
    in light of the crucial nature of P’s testimony, the serious nature of the
    crimes, and the state’s knowledge that P was a reluctant witness who
    had been compelled to testify at the probable cause hearing by court
    order, this court could not conclude that the state’s efforts to locate P
    were as vigorous as they would have been if the state did not have her
    former testimony to rely on, as H conducted electronic searches for P
    in only three content limited databases, the usefulness of his searches
    in two of those databases was of questionable value in light of H’s
    knowledge that P was a New York resident with no known criminal
    record, H’s search in the third database was limited to only basic location
    information, H did not search any New York governmental databases
    for P’s motor vehicle, social service, housing court, family court, or
    child support records, H did not conduct any routine Internet searches
    on Google or social media sites, once H had forwarded the three
    addresses he found for P to G, he never spoke to or requested that G,
    who visited the addresses associated with P only during normal business
    hours, make any additional efforts to locate her by returning to the
    addresses at other times of day, speaking with neighbors or landlords,
    or conducting surveillance, and, after G failed to locate P at any of the
    three addresses that H had provided, the state made no further efforts
    to locate her.
    2. The admission of S’s expert testimony did not violate the defendant’s sixth
    amendment right to confrontation because, even if it was predicated in
    part on testimonial hearsay purportedly contained in a ballistic report
    prepared by a former employee of the state forensics laboratory and
    photographs that S had reviewed, such hearsay was not admitted into
    evidence or otherwise introduced to the jury for the truth of the matter
    asserted; although the jury had been informed that S had reviewed
    certain reports and photographs in preparation of his testimony, neither
    those materials nor the out-of-court statements that they contained were
    admitted into evidence as an exhibit or through the conduit of S’s in-
    court testimony, the jury was not informed of the nature of the reports,
    who had prepared them, or whether S’s opinions were consistent with
    those contained in the reports, and the trial court sustained the defen-
    dant’s objection when the state attempted to question S as to which
    materials he had reviewed and ruled that S’s testimony must be limited
    to S’s own conclusions; accordingly, this court concluded that S applied
    his training and experience to reach an independent judgment about
    the ballistic evidence, the basis of which could be tested through cross-
    examination at the defendant’s trial, and that S did not merely transmit
    the testimonial hearsay purportedly contained in the ballistic report
    prepared and photographs generated by the former employee of the
    state forensics laboratory.
    (Two justices concurring in part and dissenting in part in one opinion)
    Argued January 23, 2019—officially released January 28, 2020
    Procedural History
    Substitute information charging the defendant with
    the crimes of felony murder, home invasion, conspiracy
    to commit home invasion, burglary in the first degree,
    conspiracy to commit burglary in the first degree,
    attempt to commit robbery in the first degree, conspir-
    acy to commit robbery in the first degree, and assault
    in the first degree, brought to the Superior Court in the
    judicial district of Hartford, and tried to the jury before
    Dewey, J.; subsequently, the court denied the defen-
    dant’s motions to preclude certain evidence; verdict of
    guilty; thereafter, the court vacated the jury’s finding
    of guilty as to conspiracy to commit burglary in the
    first degree and conspiracy to commit robbery in the
    first degree and rendered judgment thereon, from which
    the defendant appealed to the Appellate Court, Alvord,
    Prescott and Pellegrino, Js., which affirmed the judg-
    ment of the trial court, and the defendant, on the grant-
    ing of certification, appealed to this court. Reversed;
    new trial.
    Raymond L. Durelli, assigned counsel, for the appel-
    lant (defendant).
    Kathryn W. Bare, assistant state’s attorney, with
    whom, on the brief, were Gail P. Hardy, state’s attor-
    ney, John F. Fahey and Robert Diaz, senior assistant
    state’s attorneys, and Allen M. Even, certified legal
    intern, for the appellee (state).
    Opinion
    ECKER, J. The defendant, Horvil F. Lebrick, claims in
    this certified appeal that the Appellate Court improperly
    affirmed his judgment of conviction because the trial
    testimony of two witnesses should have been excluded
    from evidence under the Connecticut Code of Evidence
    and the confrontation clause of the sixth amendment
    to the United States constitution.1 Specifically, the
    defendant contends that (1) the state failed to establish
    adequately that a nonappearing witness named Keisha
    Parks was unavailable to testify at trial, and, therefore,
    her former testimony improperly was admitted under
    § 8-6 (1) of the Connecticut Code of Evidence2 and
    in violation of the confrontation clause, and (2) the
    testimony of James Stephenson, the state’s expert wit-
    ness on firearm and tool mark identification, was predi-
    cated on inadmissible hearsay and, therefore, improp-
    erly was admitted in violation of the confrontation
    clause. We agree with the defendant that the admission
    of Parks’ former testimony violated his constitutional
    right of confrontation, but we disagree that the admis-
    sion of Stephenson’s testimony was unconstitutional.
    We therefore reverse the judgment of the Appellate
    Court and remand the case for a new trial.
    The jury reasonably could have found the following
    facts. During the early morning hours of May 6, 2010,
    the defendant and his cousins, twin brothers Andrew
    and Andraw Moses, traveled from New York to East
    Hartford in a Ford Econoline van driven by a fourth,
    unidentified man. At approximately 8 a.m., the van
    arrived at an apartment complex located at 115 Nutmeg
    Avenue, where a purported drug dealer, Omari Barrett,
    rented an apartment on the third floor. The plan was
    to rob Barrett of money and/or drugs. In order to gain
    entry into the apartment, the Moses twins dressed as
    workmen and armed themselves with guns. The defen-
    dant accompanied the Moses twins to Barrett’s apart-
    ment, where they knocked on the door multiple times.
    When no one answered, the defendant kicked the door
    open, and the three men entered the apartment.
    The victim, Shawna Lee Hudson, was alone in the
    apartment at the time. The victim telephoned Barrett
    when the three men initially knocked on the door, and
    Barrett informed her that he had not requested any
    maintenance at the apartment. Shortly thereafter, the
    victim called Barrett a second time and told him that
    the three men were ‘‘breaking down the door to get in
    the apartment.’’ Barrett informed the victim that he was
    on his way and instructed her to arm herself with a
    .357 magnum revolver located inside the apartment.
    Soon thereafter, the victim called Barrett a third time
    and whispered to him that the men were inside the
    apartment and that she was hiding in a closet. At this
    point, Barrett had arrived at the apartment complex
    and was on his way up to the third floor. Barrett could
    hear a voice in the background on the open phone line
    of someone saying, ‘‘ ‘[w]here’s the money? Shut the
    fuck up,’ ’’ and then the phone line went dead.
    Barrett, who was armed with a nine millimeter
    revolver, arrived outside the apartment and noticed that
    the door was ajar and looked ‘‘like somebody [had]
    kicked it in . . . .’’ After entering the apartment, Bar-
    rett encountered the Moses twins, whom he fatally shot.
    Barrett then called out to the victim to ask how many
    people were left in the apartment, and she responded
    that there was one more. Barrett and the defendant
    then exchanged gunfire, and Barrett was shot twice—
    once in the leg and once in the arm. Barrett retreated
    from the apartment to an alcove down the hallway by
    the elevators. He then heard a single gunshot and saw
    someone exit the apartment and flee in the opposite
    direction down the hallway. Barrett returned to the
    apartment, where he found the victim, who had been
    shot fatally once in the chest. Additional facts will be
    set forth as necessary.
    Following a jury trial, the defendant was convicted
    of felony murder in violation of General Statutes (Rev.
    to 2009) § 53a-54c, home invasion in violation of General
    Statutes §§ 53a-8 (a) and 53a-100aa (a) (2), conspiracy
    to commit home invasion in violation of General Stat-
    utes §§ 53a-48 (a) and 53a-100aa (a) (2), burglary in the
    first degree in violation of General Statutes §§ 53a-8 (a)
    and 53a-101 (a) (1), attempt to commit robbery in the
    first degree in violation of General Statutes §§ 53a-49
    (a) (2) and 53a-134 (a) (2), and assault in the first degree
    in violation of General Statutes §§ 53a-8 (a) and 53a-59
    (a) (5).3 The trial court sentenced the defendant to a
    total effective sentence of ninety years of impris-
    onment.
    The Appellate Court affirmed the defendant’s judg-
    ment of conviction. See State v. Lebrick, 
    179 Conn. App. 221
    , 246, 
    178 A.3d 1064
    (2018). As relevant to the issues
    before us, the Appellate Court determined that the trial
    court had not abused its discretion in admitting the
    former testimony of Parks, a witness who did not
    appear at trial but who reluctantly testified at the defen-
    dant’s probable cause hearing, because the state had
    made a diligent and good faith effort to secure her
    attendance at the defendant’s trial. 
    Id., 229–36. The
    Appellate Court held, for this reason, that Parks’ former
    testimony was admissible under both § 8-6 (1) of the
    Connecticut Code of Evidence and the confrontation
    clause. 
    Id., 233, 236.
    The Appellate Court also deter-
    mined that the admission of Stephenson’s expert testi-
    mony did not violate the defendant’s sixth amendment
    right of confrontation because, even if Stephenson had
    relied on testimonial hearsay in formulating his expert
    opinion, he was ‘‘fully available for cross-examination
    at trial regarding his own scientific conclusions and the
    factual basis underpinning his opinion.’’4 
    Id., 245. This
    certified appeal followed.5
    I
    The defendant’s first claim of error involves the
    admissibility of the former testimony of Parks, who was
    Andrew Moses’ fiancée at the time of the underlying
    events. The following additional facts and procedural
    history are relevant to our review of this claim.
    After hearing a rumor on May 6, 2010, that the Moses
    twins had been killed in Connecticut, Parks contacted
    the East Hartford Police Department to find out if the
    rumor was true. Two days later, Parks provided the
    East Hartford police with a written statement, and, after
    the defendant’s arrest, she reluctantly testified at his
    probable cause hearing pursuant to a court order.
    Parks testified to the following facts at the defen-
    dant’s probable cause hearing. On the evening of May
    5, 2010, Parks observed the Moses twins enter the defen-
    dant’s Ford Econoline van in Brooklyn.6 The next day,
    after learning that the twins had been killed, Parks and
    Andraw Moses’ wife spent several hours searching for
    the defendant. The defendant finally contacted Parks
    and Andraw Moses’ wife, and they then met the defen-
    dant in Brooklyn. The defendant explained at the meet-
    ing that he had traveled to Connecticut with the twins
    and the unidentified driver of the van to commit a rob-
    bery. After knocking on an apartment door and receiv-
    ing no answer, the defendant kicked the door open
    and found a girl inside the apartment with a gun. The
    defendant grabbed the gun from the girl and made his
    way to another room of the apartment. The defendant
    heard gunshots while he was in the other room, and one
    of the Moses twins went to investigate. The defendant
    heard another shot, and the other twin followed his
    brother to investigate. The defendant then heard
    another shot, followed by the shooter’s asking the girl
    how many people were left in the apartment. The defen-
    dant proceeded to shoot his way out of the apartment
    using the gun he had taken from the girl, observing the
    twins’ bodies lying on the floor as he left. He then exited
    the building, told the driver of the van that the twins
    were dead, and fled to New York.
    In late August or early September of 2014,7 around
    the time that jury selection in the defendant’s trial com-
    menced, the state began to search for Parks in order
    to secure her in-court testimony at the defendant’s
    trial. Emory L. Hightower, a police inspector with the
    state’s criminal justice division in the Hartford state’s
    attorney’s office, first attempted to contact Parks at
    her last known address and phone number. When that
    effort proved unsuccessful, Hightower conducted an
    electronic search for Parks in the Hartford Police
    Department’s local in-house computer database. The
    search yielded no results. Hightower next searched
    the National Crime Information Center (NCIC) data-
    base, a national database administered by the Federal
    Bureau of Investigation and utilized by law enforcement
    to search for an individual’s prior criminal records.
    After discovering no criminal record for Parks in the
    NCIC database, Hightower used a search engine called
    CLEAR, operated by the Thomson Reuters Corporation,
    which aggregates publicly available data. Through the
    CLEAR search, Hightower obtained two addresses for
    Parks in New York and several phone numbers. High-
    tower called the phone numbers, but two were not in
    service, and one was not receiving phone calls.
    An interstate summons was prepared to compel
    Parks’ attendance at the defendant’s trial. Hightower
    e-mailed the interstate summons to the Kings County
    District Attorney’s Office and requested service on
    Parks. The same e-mail included a memorandum con-
    taining the addresses and phone numbers that High-
    tower had found in the CLEAR system for Parks.
    Hightower also provided the Kings County District
    Attorney’s Office with the last known address of Parks’
    mother, who lived in Brooklyn, New York.
    Frank Garguilo, an investigator with the Kings County
    District Attorney’s Office, was assigned the task of serv-
    ing the interstate summons on Parks. Garguilo was not
    asked to conduct an independent investigation to ascer-
    tain Parks’ whereabouts and did not do so. Over the
    course of two days, September 25 and 26, 2014, Garguilo
    visited each of the addresses associated with Parks.
    At approximately 12:30 p.m. on September 25, 2014,
    Garguilo visited the first address that Hightower had
    provided him for Parks in Brooklyn. After being let into
    the building by a neighbor, he knocked on the door
    of the apartment believed to belong to Parks, but he
    received no answer. Garguilo then called one of the
    phone numbers associated with Parks, but the greeting
    on the voicemail indicated that the phone number
    belonged to an individual named Miriam Augustine.
    Garguilo left a message asking Augustine to return his
    call but never received a response. Garguilo then trav-
    eled to the last known address of Parks’ mother, also
    in Brooklyn, but no one was home. Garguilo returned
    to Parks’ Brooklyn address for a second time at approxi-
    mately 5 p.m., but again no one was home. The next
    morning, September 26, 2014, Garguilo made a third
    and final visit to Parks’ Brooklyn address. When he was
    unsuccessful, he traveled to the last address for Parks
    that Hightower had provided, in the Jamaica neighbor-
    hood of Queens. No one was home at that location,
    either. Garguilo did not encounter anyone, at any of
    the addresses, whom he could question regarding
    Parks’ whereabouts.
    At the defendant’s trial, the state sought to admit
    Parks’ former testimony from the probable cause hear-
    ing pursuant to § 8-6 (1) of the Connecticut Code of
    Evidence, which permits the admission of ‘‘[t]estimony
    given as a witness at another hearing of the same or a
    different proceeding’’ if ‘‘the declarant is unavailable as
    a witness . . . .’’ The defendant moved to exclude
    Parks’ former testimony, contending that the state had
    failed to establish Parks’ unavailability under § 8-6 (1)
    because it had not ‘‘exercised due diligence and made
    a good faith effort to procure [her] attendance’’ at trial.
    The defendant further claimed that the admission of
    Parks’ former testimony would violate his sixth amend-
    ment right of confrontation pursuant to Crawford v.
    Washington, 
    541 U.S. 36
    , 68–69, 
    124 S. Ct. 1354
    , 158 L.
    Ed. 2d 177 (2004).
    The trial court conducted a hearing on the defen-
    dant’s motion to exclude Parks’ former testimony, at
    which it heard the testimony of Hightower and Garguilo,
    as previously described, regarding their efforts to locate
    Parks. The trial court also heard testimony from Erin
    Tiernam, a CLEAR product specialist employed by the
    Thomson Reuters Corporation, regarding how CLEAR
    operates and the information available through it. Tier-
    nam explained that CLEAR offers different subscription
    levels. The ‘‘basic subscription’’ includes ‘‘location ser-
    vices,’’ such as credit headers and utility hookups,
    whereas the ‘‘second level includes the more detailed
    reports like . . . lawsuits, liens, judgments, [and] crim-
    inal records.’’ There is also an additional option to add
    ‘‘a web analytic search,’’ which aggregates social media
    data, such as ‘‘Facebook pages, LinkedIn pages, and
    also just somebody’s general presence on the web.’’
    Tiernam did not know what subscription level High-
    tower had used to search for information about Parks.
    Defense counsel argued that the state’s efforts to
    procure Parks’ in-court testimony were insufficient to
    meet the evidentiary and constitutional unavailability
    standard because the state had failed to search (1)
    social media websites, such as Facebook, (2) New York
    State Department of Motor Vehicles records, (3) New
    York State Department of Corrections and Community
    Supervision records, (4) housing and/or eviction
    records, (5) Social Security Administration records, (6)
    Immigration and Naturalization Service records, (7)
    records of protective orders or child support orders,
    and (8) for Parks’ relatives, friends, and/or landlords,
    who might be aware of her whereabouts. The trial court
    disagreed, implicitly finding that the state’s efforts to
    locate Parks were sufficient to establish her unavailabil-
    ity under both our rules of evidence and the confronta-
    tion clause of the sixth amendment.8 Parks’ former testi-
    mony was read to the jury. On appeal, the defendant
    contends that Parks’ former testimony improperly was
    admitted in violation of § 8-6 (1) of the Connecticut
    Code of Evidence and the confrontation clause of the
    sixth amendment, both of which require the state to
    make a reasonable, diligent, and good faith effort to
    secure the in-court testimony of an unavailable declar-
    ant before the declarant’s former testimony is admitted.
    A
    As a preliminary matter, we address the standard of
    review applicable to the defendant’s evidentiary and
    constitutional claims. We previously have observed in
    general terms that ‘‘[t]he trial court has broad discretion
    in determining whether the proponent has shown a
    declarant to be unavailable. A trial court’s determina-
    tion of the unavailability of a witness will be overturned
    only if there has been a clear abuse of discretion.’’ State
    v. Lapointe, 
    237 Conn. 694
    , 738, 
    678 A.2d 942
    , cert.
    denied, 
    519 U.S. 994
    , 
    117 S. Ct. 484
    , 
    136 L. Ed. 2d 378
    (1996); accord State v. Rivera, 
    221 Conn. 58
    , 62, 
    602 A.2d 571
    (1992). We explained that this deferential stan-
    dard of review is appropriate ‘‘[i]n light of the [fact
    bound] nature of the [unavailability] inquiry . . . .’’
    State v. Schiappa, 
    248 Conn. 132
    , 141, 
    728 A.2d 466
    ,
    cert. denied, 
    528 U.S. 862
    , 
    120 S. Ct. 152
    , 
    145 L. Ed. 2d 129
    (1999); see 
    id., 145–58 (examining
    unavailability
    under statements against penal interest exception to
    hearsay rule); see also State v. Wright, 
    107 Conn. App. 85
    , 89, 
    943 A.2d 1159
    (holding that, under § 8-6 [1], ‘‘the
    court’s assessment of whether the actions of the state
    in attempting to find the witness properly could be
    characterized as having been undertaken with due dili-
    gence involve[s] a ‘judgment call’ by the court’’ properly
    reviewed under ‘‘the abuse of discretion standard’’),
    cert. denied, 
    287 Conn. 914
    , 
    950 A.2d 1291
    (2008). It
    is clear that the abuse of discretion standard applies
    specifically to a trial court’s determination that a wit-
    ness is ‘‘unavailable’’ to testify under § 8-6 (1) of the
    Connecticut Code of Evidence. See, e.g., State v. Mor-
    quecho, 
    138 Conn. App. 841
    , 859 n.8, 
    54 A.3d 609
    (reviewing defendant’s challenge to admission of evi-
    dence under § 8-6 [1] for abuse of discretion but noting
    that ‘‘[t]he defendant does not raise a Crawford claim
    and did not advance arguments of that nature before
    the trial court’’), cert. denied, 
    307 Conn. 941
    , 
    56 A.3d 948
    (2012); State v. 
    Wright, supra
    , 87–88 (rejecting
    defendant’s claim that reviewing court ‘‘should employ
    a plenary standard of review’’ but noting that defendant
    only raised evidentiary claim and did ‘‘not rais[e] a
    Crawford confrontation clause issue’’).
    It is less clear whether this deferential standard of
    review applies with respect to a defendant’s confronta-
    tion clause claim challenging the admissibility of out-of-
    court statements of an allegedly unavailable declarant
    pursuant to Crawford v. 
    Washington, supra
    , 
    541 U.S. 36
    . In our view, the abuse of discretion standard is at
    odds with the axiomatic principle that ‘‘question[s] of
    constitutional law . . . [are] subject to plenary
    review.’’ State v. Kirby, 
    280 Conn. 361
    , 378, 
    908 A.2d 506
    (2006); see also State v. Simpson, 
    286 Conn. 634
    ,
    651, 
    945 A.2d 449
    (2008) (‘‘we exercise plenary review
    over whether the trial court properly concluded that
    the admission of the videotapes did not violate the
    defendant’s confrontation clause rights under Craw-
    ford’’). We therefore take this opportunity to clarify the
    appropriate standard of review governing such claims.
    Consistent with the case law of the United States
    Circuit Courts of Appeals, we conclude that ‘‘[t]he
    issues of the unavailability of the witness and the rea-
    sonableness of the [s]tate’s efforts to produce the wit-
    ness [under] the [c]onfrontation [c]lause [of] the [s]ixth
    [a]mendment . . . are mixed questions of law and fact
    . . . .’’ Hamilton v. Morgan, 
    474 F.3d 854
    , 858 (6th
    Cir.), cert. denied, 
    552 U.S. 953
    , 
    128 S. Ct. 380
    , 169 L.
    Ed. 2d 268 (2007); see also McCandless v. Vaughn, 
    172 F.3d 255
    , 265 (3d Cir. 1999) (‘‘the ultimate issue of
    unavailability for purposes of the [c]onfrontation
    [c]lause is a mixed question of fact and law’’ [internal
    quotation marks omitted]); Martinez v. Sullivan, 
    881 F.2d 921
    , 926 (10th Cir. 1989) (noting that ‘‘the ultimate
    issue of unavailability for purposes of the [c]onfronta-
    tion [c]lause is a mixed question of fact and law’’), cert.
    denied sub nom. Martinez v. Tansy, 
    493 U.S. 1029
    , 
    110 S. Ct. 740
    , 
    107 L. Ed. 2d 758
    (1990); Burns v. Clusen, 
    798 F.2d 931
    , 942 (7th Cir. 1986) (holding that unavailability
    under confrontation clause is ‘‘a mixed question of law
    and fact’’).9 As the United States Court of Appeals for
    the Seventh Circuit has explained, a ‘‘finding of ‘unavail-
    ability’ . . . has more resemblance to a ‘mixed’ deter-
    mination rather than a straight finding of fact. The issue
    takes on a constitutional dimension of its own when
    analyzed in the context of the [c]onfrontation [c]lause,
    as opposed to simply in the context of [the state’s]
    hearsay rules. A determination [of] ‘unavailability’ goes
    beyond assessments of credibility and demeanor’’ and
    ‘‘necessarily includes the ultimate legal issue at stake.’’
    Burns v. 
    Clusen, supra
    , 941. Accordingly, a trial court’s
    subordinate factual findings regarding the unavailability
    of a witness ‘‘will not be disturbed unless clearly errone-
    ous and the trial court’s legal conclusion regarding the
    applicability of the [law] in light of these facts will be
    reviewed de novo.’’ (Internal quotation marks omitted.)
    State v. DeMarco, 
    311 Conn. 510
    , 518–19, 
    88 A.3d 491
    (2014); see also State v. Marquez, 
    291 Conn. 122
    , 136,
    
    967 A.2d 56
    (relying on ‘‘federal precedent and the
    approach taken by our sister states’’ to conclude that
    ‘‘the ultimate question as to the constitutionality of . . .
    pretrial identification procedures . . . is a mixed ques-
    tion of law and fact’’ [internal quotation marks omit-
    ted]), cert. denied, 
    558 U.S. 895
    , 
    130 S. Ct. 237
    , 175 L.
    Ed. 2d 163 (2009).
    ‘‘[W]hen a question of fact is essential to the outcome
    of a particular legal determination that implicates a
    defendant’s constitutional rights, and the credibility of
    witnesses is not the primary issue, our customary defer-
    ence to the trial court’s factual findings is tempered by
    a scrupulous examination of the record to ascertain
    that the trial court’s factual findings are supported by
    substantial evidence. . . . [W]here the legal conclu-
    sions of the court are challenged, [our review is plenary,
    and] we must determine whether they are legally and
    logically correct and whether they find support in the
    facts set out in the memorandum of decision . . . .’’
    (Internal quotation marks omitted.) State v. 
    DeMarco, supra
    , 
    311 Conn. 519
    . Although ‘‘we are bound to accept
    the factual findings of the trial court unless they are
    clearly erroneous’’; State v. Mangual, 
    311 Conn. 182
    ,
    197, 
    85 A.3d 627
    (2014); the ultimate determination of
    whether a witness is ‘‘unavailable’’ for purposes of the
    confrontation clause is reviewed de novo. See 
    id. B The
    defendant claims that Parks’ former testimony
    improperly was admitted because the state failed to
    demonstrate that Parks was unavailable within the
    meaning of our rules of evidence and the confrontation
    clause of the sixth amendment. To determine whether
    a witness is unavailable for purposes of § 8-6 (1) of the
    Connecticut Code of Evidence, ‘‘this court follows the
    definition of the term ‘unavailable’ in rule 804 (a) of
    the Federal Rules of Evidence.’’ Maio v. New Haven,
    
    326 Conn. 708
    , 726, 
    167 A.3d 338
    (2017). Under rule 804
    (a), ‘‘[a] declarant is considered to be unavailable as a
    witness’’ for the purpose of admitting former testimony
    ‘‘if the declarant . . . is absent from the trial or hearing
    and the statement’s proponent has not been able, by
    process or other reasonable means, to procure . . .
    the declarant’s attendance . . . .’’ Fed. R. Evid. 804 (a)
    (5) (A). ‘‘In interpreting reasonable means, we have
    held that the proponent must exercise due diligence
    and, at a minimum, make a good faith effort to procure
    the declarant’s attendance.’’ (Internal quotation marks
    omitted.) State v. 
    Rivera, supra
    , 
    221 Conn. 62
    .
    Similarly, under the confrontation clause of the sixth
    amendment, a witness is not unavailable ‘‘ ‘unless the
    prosecutorial authorities have made a [good faith] effort
    to obtain his presence at trial.’ ’’ Hardy v. Cross, 
    565 U.S. 65
    , 69, 
    132 S. Ct. 490
    , 
    181 L. Ed. 2d 468
    (2011),
    quoting Barber v. Page, 
    390 U.S. 719
    , 725, 
    88 S. Ct. 1318
    ,
    
    20 L. Ed. 2d 255
    (1968). ‘‘ ‘The lengths to which the
    prosecution must go to produce a witness . . . is a
    question of reasonableness.’ ’’ Hardy v. 
    Cross, supra
    ,
    70, quoting Ohio v. Roberts, 
    448 U.S. 56
    , 74, 
    100 S. Ct. 2531
    , 
    65 L. Ed. 2d 597
    (1980), overruled on other grounds
    by Crawford v. Washington, 
    541 U.S. 36
    , 
    124 S. Ct. 1354
    ,
    
    158 L. Ed. 2d 177
    (2004). To demonstrate reasonable-
    ness, ‘‘the proponent must exercise due diligence and,
    at a minimum, make a good faith effort to procure
    the declarant’s attendance.’’ (Internal quotation marks
    omitted.) State v. 
    Rivera, supra
    , 
    221 Conn. 62
    .
    Former testimony therefore is inadmissible under
    both our rules of evidence and the confrontation clause
    unless the state has made a reasonable, diligent, and
    good faith effort to procure the absent witness’ atten-
    dance at trial. ‘‘This showing necessarily requires sub-
    stantial diligence. In determining whether the propo-
    nent of the declaration has satisfied this burden of
    making reasonable efforts, the court must consider
    what steps were taken to secure the presence of the
    witness and the timing of efforts to procure the declar-
    ant’s attendance.’’ State v. Lopez, 
    239 Conn. 56
    , 75, 
    681 A.2d 950
    (1996). ‘‘A proponent’s burden is to demon-
    strate a diligent and reasonable effort, not to do every-
    thing conceivable, to secure the witness’ presence.’’ 
    Id., 77–78. Indeed,
    it is always possible, in hindsight, to
    think of some ‘‘additional steps that the prosecution
    might have taken to secure the witness’ presence,’’ but
    the ‘‘[s]ixth [a]mendment does not require the prosecu-
    tion to exhaust every avenue of inquiry, no matter how
    unpromising.’’ Hardy v. 
    Cross, supra
    , 
    565 U.S. 71
    –72;
    see also Ohio v. 
    Roberts, supra
    , 
    448 U.S. 74
    (‘‘The law
    does not require the doing of a futile act. Thus, if no
    possibility of procuring the witness exists [as, for exam-
    ple, the witness’ intervening death], ‘good faith’
    demands nothing of the prosecution.’’); State v. 
    Rivera, supra
    , 
    221 Conn. 67
    (‘‘the question of whether an effort
    to locate a missing witness has been sufficiently diligent
    to declare that person unavailable is one that is inher-
    ently fact specific and always vulnerable to criticism,
    due to the fact that [o]ne, in hindsight, may always
    think of other things’’ [internal quotation marks omit-
    ted]). ‘‘But if there is a possibility, albeit remote, that
    affirmative measures might produce the declarant, the
    obligation of good faith may demand their effectua-
    tion.’’ (Emphasis in original.) Ohio v. 
    Roberts, supra
    , 74.
    C
    Turning to the merits of the defendant’s claim, we
    focus our analysis on the confrontation clause because
    the definition of unavailability is the same under both
    our rules of evidence and the confrontation clause, but
    the ultimate determination of whether the state’s efforts
    are constitutionally sufficient to establish the unavail-
    ability of the witness is a question of law reviewed de
    novo.10 See part I A of this opinion; see also State v.
    Cameron M., 
    307 Conn. 504
    , 516 n.16, 
    55 A.3d 272
    (2012)
    (recognizing our ‘‘general practice of not addressing
    constitutional questions unless their resolution is
    unavoidable’’ but nonetheless focusing analysis on con-
    frontation clause because determination of unavailabil-
    ity under our rules of evidence and confrontation clause
    ‘‘is analytically identical’’ [internal quotation marks
    omitted]), cert. denied, 
    569 U.S. 1005
    , 
    133 S. Ct. 2744
    ,
    
    186 L. Ed. 2d 194
    (2013); United States v. Tirado-Tirado,
    
    563 F.3d 117
    , 123 n.4 (5th Cir. 2009) (‘‘[t]his [c]ourt
    treats the [c]onfrontation [c]lause unavailability inquiry
    as identical to the unavailability inquiry under [r]ule
    804 [a] [5] of the Federal Rules of Evidence’’).
    ‘‘The central concern of the [c]onfrontation [c]lause
    is to ensure the reliability of the evidence against a
    criminal defendant by subjecting it to rigorous testing
    in the context of an adversary proceeding before the
    trier of fact.’’ Maryland v. Craig, 
    497 U.S. 836
    , 845,
    
    110 S. Ct. 3157
    , 
    111 L. Ed. 2d 666
    (1990). The right of
    confrontation includes (1) the physical presence of the
    witness, (2) the administration of an oath to impress
    upon the witness ‘‘the seriousness of the matter’’ and
    to guard ‘‘against the lie by the possibility of a penalty
    for perjury,’’ (3) cross-examination of the witness to
    aid in ‘‘the discovery of truth,’’ and (4) the opportunity
    for the jury ‘‘to observe the demeanor of the witness
    in making his statement, thus aiding the jury in assessing
    his credibility.’’ (Internal quotation marks omitted.) 
    Id., 845–46. The
    former testimony of an absent witness typi-
    cally was produced under oath at a proceeding at which
    the witness was subject to cross-examination, but the
    admission of this testimony nonetheless implicates con-
    cerns under the confrontation clause because its use
    deprives the jury of the opportunity to ‘‘observe closely
    the [witness’] demeanor, expressions, and intonations,
    and thereby [to] determine the [witness’] credibility.’’
    United States v. Smith, 
    928 F.3d 1215
    , 1226 (11th Cir.
    2019), cert. denied, 
    88 U.S.L.W. 3225
    (U.S. January 13,
    2020) (No. 19-361).
    ‘‘[I]n conformance with the [f]ramers’ preference for
    face-to-face accusation, the [s]ixth [a]mendment estab-
    lishes a rule of necessity. In the usual case (including
    cases [in which] prior cross-examination has occurred),
    the prosecution must either produce, or demonstrate
    the unavailability of, the declarant whose statement it
    wishes to use against the defendant.’’ Ohio v. 
    Roberts, supra
    , 
    448 U.S. 65
    . As we explained in part I B of this
    opinion, to demonstrate the unavailability of a witness,
    the state must establish that it made a reasonable, dili-
    gent, and good faith effort to procure the witness’ atten-
    dance at trial. See Hardy v. 
    Cross, supra
    , 
    565 U.S. 69
    (‘‘a witness is not unavailable for purposes of the . . .
    confrontation requirement unless the prosecutorial
    authorities have made a [good faith] effort to obtain his
    presence at trial’’ [internal quotation marks omitted]);
    Ohio v. 
    Roberts, supra
    , 74 (‘‘[t]he lengths to which the
    prosecution must go to produce a witness . . . is a
    question of reasonableness,’’ and ‘‘[t]he ultimate ques-
    tion is whether the witness is unavailable despite [good
    faith] efforts undertaken prior to trial to locate and
    present that witness’’ [internal quotation marks
    omitted]).
    ‘‘[T]here is no [bright line] rule for reasonableness,
    and [the] reasonableness inquiry necessarily is [fact
    specific] and examines the totality of the factual circum-
    stances of each particular case.’’ United States v. 
    Smith, supra
    , 
    928 F.3d 1228
    ; see also State v. 
    Rivera, supra
    ,
    
    221 Conn. 67
    (emphasizing ‘‘fact specific’’ nature of
    unavailability inquiry). Although the United States Cir-
    cuit Courts of Appeals have rejected a ‘‘per se rule’’ or
    ‘‘categorical approach’’ when it comes to assessing the
    reasonableness of efforts to produce a missing witness;
    United States v. Burden, 
    934 F.3d 675
    , 689 (D.C. Cir.
    2019); they have identified four objective criteria to
    guide the reasonableness inquiry. ‘‘First, the more cru-
    cial the witness, the greater the effort required to secure
    his attendance. . . . Second, the more serious the
    crime for which the defendant is being tried, the greater
    the effort the [state] should put forth to produce the
    witness at trial. . . . Third, where a witness has special
    reason to favor the prosecution, such as an immunity
    arrangement in exchange for cooperation, the defen-
    dant’s interest in confronting the witness is stronger.
    . . . Fourth, a good measure of reasonableness is to
    require the [s]tate to make the same sort of effort to
    locate and secure the witness for trial that it would have
    made if it did not have the prior testimony available.’’
    (Citations omitted.) Cook v. McKune, 
    323 F.3d 825
    ,
    835–36 (10th Cir. 2003); see also McCandless v. 
    Vaughn, supra
    , 
    172 F.3d 266
    (‘‘Confrontation [c]lause concerns
    are heightened and courts insist on more diligent efforts
    by the prosecution where a ‘key’ or ‘crucial’ witness’
    testimony is involved. . . . The defendant’s interest in
    confrontation is, of course, further heightened where
    the absent witness has special reason to give testimony
    favorable to the prosecution. . . . Finally, special sen-
    sitivity to [c]onfrontation [c]lause concerns is appro-
    priate where the consequences of a conviction based
    on the absent witness’ testimony are grave.’’ [Citations
    omitted.]); United States v. Quinn, 
    901 F.2d 522
    , 529
    (6th Cir. 1990) (‘‘[c]onfrontation [c]lause considerations
    are especially cogent when the testimony of a witness is
    critical to the prosecution’s case against the defendant’’
    [internal quotation marks omitted]); United States v.
    Lynch, 
    499 F.2d 1011
    , 1023 (D.C. Cir. 1974) (govern-
    ment’s duty to search for missing witness ‘‘in good faith
    and with reasonable diligence and care’’ ordinarily ‘‘will
    require a search equally as vigorous as that which the
    government would undertake to find a critical witness
    if it has no preliminary hearing testimony to rely [on]
    in the event of ‘unavailability’ ’’); Brooks v. United
    States, 
    39 A.3d 873
    , 884 (D.C. 2012) (‘‘[t]he government’s
    obligation to take steps to produce the witness ha[s]
    to correspond to the importance of the witness and
    the potential prejudice to the defendant if she [does]
    not testify’’).
    We believe that this approach provides useful guid-
    ance and structure, and we will employ these four crite-
    ria here to assess whether the state’s efforts to locate
    Parks were sufficient to protect the defendant’s sixth
    amendment right of confrontation.11 First, as the state
    conceded at oral argument before this court,12 Parks
    was an important witness who provided key testimony
    that was not provided by any other witness, namely,
    the defendant’s confession that he kicked in the door
    to Barrett’s apartment, took the gun away from the
    victim, and shot his way out of the apartment.13 Parks’
    testimony directly contradicted the defendant’s state-
    ment to the police, in which he admitted that he was
    present in the apartment at the time of the shooting
    but maintained that he was there to help the Moses
    twins ‘‘move some boxes’’ when ‘‘a guy showed up
    shooting.’’ The defendant stated to the police that he
    did not have a gun and did not know that the Moses
    twins were armed with guns before the shooting began.
    The defendant explained that he escaped from the
    apartment by following behind some other men ‘‘as they
    shot their way out of the apartment.’’
    Parks’ testimony provided the state with crucial,
    inculpatory evidence regarding the defendant’s role in
    the commission of the crimes—the defendant’s confes-
    sion that he intended to commit a robbery, was armed
    with a gun, and was one of the shooters. Given that
    ‘‘[a] defendant’s confession is probably the most proba-
    tive and damaging evidence that can be admitted against
    him’’; (internal quotation marks omitted) Arizona v.
    Fulminante, 
    499 U.S. 279
    , 292, 
    111 S. Ct. 1246
    , 113 L.
    Ed. 2d 302 (1991); we conclude that the first factor
    weighs in favor of the defendant. See, e.g., State v.
    Lockhart, 
    298 Conn. 537
    , 597, 
    4 A.3d 1176
    (2010) (‘‘con-
    fessions are such powerful forms of evidence’’ [internal
    quotation marks omitted]); State v. Iban C., 
    275 Conn. 624
    , 645, 
    881 A.2d 1005
    (2005) (‘‘a confession, if suffi-
    ciently corroborated, is the most damaging evidence of
    guilt’’ [internal quotation marks omitted]).
    Turning to the second factor, we note that the defen-
    dant was charged with extremely serious crimes—
    namely, felony murder, home invasion, conspiracy to
    commit home invasion, burglary in the first degree,
    attempt to commit robbery in the first degree, and
    assault in the first degree—and the penalties he faced
    were severe. The charge of felony murder alone carries
    a potential sentence of life imprisonment. See State v.
    Adams, 
    308 Conn. 263
    , 265, 
    63 A.3d 934
    (2013) (holding
    that felony murder ‘‘is a class A felony and, therefore,
    is punishable by a term of imprisonment of twenty-five
    years to life’’). In a case such as this one, ‘‘it is fair to
    ask more of the prosecution than in a situation involving
    significantly less serious consequences.’’ McCandless
    v. 
    Vaughn, supra
    , 
    172 F.3d 266
    . The second factor there-
    fore favors the defendant.
    Although the third factor weighs in favor of the state
    because the record does not reflect that Parks
    ‘‘receive[d] any consideration from the government for
    her testimony’’; United States v. 
    Smith, supra
    , 
    928 F.3d 1242
    ; we conclude that the fourth factor, like the first
    two, favors the defendant. Given the crucial nature of
    Parks’ testimony and the serious nature of the crimes
    charged, we cannot conclude that the state’s efforts to
    locate Parks were ‘‘as vigorous’’ as they would have
    been ‘‘if it ha[d] no preliminary hearing testimony to
    rely [on] in the event of ‘unavailability.’ ’’ United States
    v. 
    Lynch, supra
    , 
    499 F.2d 1023
    . The state knew that
    Parks was a crucial and reluctant witness whose testi-
    mony at the probable cause hearing had to be procured
    by court order but nonetheless did not keep apprised
    of her whereabouts or begin searching for her until the
    end of August or beginning of September, 2014, shortly
    before jury selection began. See footnote 7 of this opin-
    ion. When Hightower began to try and locate Parks, his
    efforts were confined to a computer search of only
    three content limited electronic databases, each of
    which contained relatively narrow categories of infor-
    mation. Hightower did not use the most basic Google
    search engine to locate Parks or even attempt to access
    any of the most popular social media sites, such as
    Facebook. Although Hightower knew that Parks was a
    New York resident, he did not search any New York
    state governmental databases to look for routine infor-
    mation, such as motor vehicle, social service, housing
    court, family court, or child support records. He did
    not use the information in his possession about Parks’
    last known addresses to learn whether she owned her
    own home or had a landlord who might have knowledge
    of her whereabouts. Nor did he ever ask anyone else
    to pursue any of these basic avenues of inquiry.
    Instead, Hightower conducted his investigation by
    searching three content limited databases available on
    his work computer. He began with the Hartford Police
    Department’s local in-house computer database, which,
    unsurprisingly, yielded no results for Parks, a New York
    resident. Hightower then turned his attention to two
    national computer databases—NCIC and CLEAR. The
    first, NCIC, contains only information about individuals
    with prior criminal and/or arrest records. There is no
    evidence that Parks had such a record, and this particu-
    larized search also failed to return any useful informa-
    tion. The second database, CLEAR, contains different
    types of information depending on the subscription
    level purchased, and, although the subscription levels
    beyond ‘‘basic’’ provide access to more robust informa-
    tion, the state failed to present evidence establishing
    what subscription level Hightower had used to search
    for Parks. The evidence indicates that Hightower’s
    search did not encompass ‘‘detailed reports like . . .
    lawsuits, liens, [and] judgments’’ or ‘‘social media infor-
    mation.’’14
    In the digital age, a vast amount of information is
    ‘‘[nonterrestrial] and borderless,’’ thus enabling the gov-
    ernment ‘‘to do more, and to do it better, faster, and
    cheaper than before’’ by conducting searches via com-
    puter rather than pounding the pavement to locate
    paper records, brick and mortar locations, and flesh
    and blood witnesses or informants. L. Donohue, ‘‘The
    Fourth Amendment in a Digital World,’’ 71 N.Y.U. Ann.
    Surv. Am. L. 553, 554 (2016). A vast amount of informa-
    tion can be accessed in a short amount of time using
    minimal physical effort. But this is true only if the proper
    electronic resources are used and the operator uses
    those resources properly. The efficacy of computer
    research necessarily is limited by the contents of the
    databases searched. In the present case, Hightower
    searched only three computer databases, two of which
    were of questionable value in locating a New York resi-
    dent with no known criminal record, and the third of
    which we are compelled to conclude included only
    ‘‘basic’’ location information, such as credit headers
    and utility hookups. See footnote 14 of this opinion.
    The on the ground efforts were equally anemic. Once
    Hightower acquired two possible addresses for Parks
    and one for her mother, he forwarded those addresses
    to Garguilo for service of the interstate summons. High-
    tower never spoke with Garguilo and made no request
    that Garguilo or anyone else in New York undertake
    any investigative efforts, knock on doors, talk with
    neighbors, locate a landlord, follow any leads, or con-
    duct the most minimal surveillance. Garguilo visited
    the addresses only during normal working hours, when
    most people with a nine-to-five job would not be
    expected to be at home. Compare Hardy v. 
    Cross, supra
    , 
    565 U.S. 68
    (no confrontation clause violation
    when state visited witness’ residence ‘‘on numerous
    occasions, approximately once every three days, at dif-
    ferent hours of the day and night’’), with United States
    v. 
    Quinn, supra
    , 
    901 F.2d 528
    (government’s efforts
    were insufficient to establish witness’ unavailability
    because government visited her apartment only twice,
    talked to her apartment manager and neighbor, drove
    by her mother’s house, and talked to her mother on
    phone). No follow-up was requested after Garguilo
    reported back regarding his lack of success, and no
    further efforts were made to locate Parks.
    The minimal effort undertaken by the state does not
    qualify as diligent. If the state did not already have
    Parks’ former testimony in hand, we consider it very
    unlikely that a supervisor would have accepted High-
    tower’s efforts without requiring more. Although we do
    not doubt the sincerity of the state’s efforts to secure
    Parks’ attendance at trial, we nonetheless find ourselves
    firmly of the view, on this record, that the state’s ‘‘unen-
    thusiastic’’; United States v. 
    Quinn, supra
    , 
    901 F.2d 528
    ;
    and ‘‘perfunctory’’ efforts are insufficient to meet the
    ‘‘relatively high good faith standard’’ of the confronta-
    tion clause. United States v. Mann, 
    590 F.2d 361
    , 367
    (1st Cir. 1978); see 
    id. (explaining that
    ‘‘perfunctory
    efforts’’ are insufficient under confrontation clause
    because, otherwise, prosecutorial authorities would
    have incentive to ‘‘discourage attempts to bring the
    witness to trial so long as the government is satisfied
    with what is in the transcript’’). Because Parks was an
    important witness and the criminal charges against the
    defendant were of the most serious nature, ‘‘we are left
    with the firm conviction that the [state’s] efforts to
    [ensure] [Parks’] presence would have been far less
    casual had the shoe been on the other foot. If the [state]
    had not had [Parks’] preliminary hearing testimony and
    had needed [Parks’] presence at trial, we are confident
    that the resources and effort devoted to finding [her]
    prior to trial would have been greater than they in fact
    were. To countenance such a disparity would ill serve
    the interests protected by the [c]onfrontation [c]lause.’’
    McCandless v. 
    Vaughn, supra
    , 
    172 F.3d 269
    ; see also
    Cook v. 
    McKune, supra
    , 
    323 F.3d 840
    (explaining that,
    ‘‘[i]f the [s]tate’s feeble exertions’’ to procure the atten-
    dance of crucial witness in murder case ‘‘can be called
    a [good faith] effort,’’ then ‘‘the [s]ixth [a]mendment
    protections . . . would be toothless’’).
    We cannot agree with the dissenting opinion that the
    state’s efforts in this case were ‘‘solidly on the spectrum
    of those deemed to be reasonable and in good faith
    by Connecticut and federal courts.’’ As we explained
    previously, the reasonableness of the state’s efforts
    must be ‘‘evaluated with a sensitivity to the surrounding
    circumstances and the defendant’s interest in confront-
    ing the absent witness.’’ McCandless v. 
    Vaughn, supra
    ,
    
    172 F.3d 266
    . In cases in which ‘‘a ‘key’ or ‘crucial’
    witness’ testimony is involved’’ and in which ‘‘the conse-
    quences of a conviction based on the absent witness’
    testimony are grave,’’ ‘‘[c]onfrontation [c]lause con-
    cerns are heightened and courts insist on more diligent
    efforts by the prosecution . . . .’’ Id.; see also United
    States v. 
    Lynch, supra
    , 
    499 F.2d 1023
    –24 (holding that
    government’s efforts to find sole eyewitness to murder
    were not ‘‘as vigorous’’ as they would have been in
    absence of witness’ prior testimony, even though wit-
    ness was served with subpoena and detectives interro-
    gated her grandmother and went to apartment at which
    she allegedly could be found multiple times); Brooks v.
    United 
    States, supra
    , 
    39 A.3d 884
    (‘‘[t]he government’s
    obligation to take steps to produce the witness ha[s]
    to correspond to the importance of the witness and the
    potential prejudice to the defendant if she [does] not
    testify’’); State v. Lee, 
    83 Haw. 267
    , 279–80, 
    925 P.2d 1091
    (1996) (state’s ‘‘lackluster efforts’’ to find crucial
    witnesses to murder were insufficient to establish their
    unavailability under confrontation clause because,
    among other things, state failed to search for their ‘‘driv-
    er’s license or motor vehicle registration’’ or show ‘‘any
    follow-up’’ after visit to one witness’ last known
    address); State v. Maben, 
    132 N.J. 487
    , 503–504, 
    626 A.2d 63
    (1993) (The state’s ‘‘minimal search’’ efforts
    were insufficient to establish the unavailability of the
    child sexual assault victim because ‘‘[t]he [s]tate [nei-
    ther] asked the post office whether the family had left
    a forwarding address, nor [asked] neighbors for the
    names of family members who might know of the fami-
    ly’s location. The [s]tate never checked to see whether
    the mother, who had received welfare in New Jersey,
    had applied for benefits in Houston, [Texas] which was
    the logical place to check because prosecutors had an
    indication that the family had moved there . . . . [T]he
    [s]tate did not ask the Houston police for assistance in
    locating the family, other than to provide the police
    with one address.’’ [Citation omitted.]). Although High-
    tower’s efforts to locate Parks might have been suffi-
    cient to demonstrate her unavailability if her testimony
    had been peripheral in its importance or if the crimes
    charged had not been grave; see, e.g., State v. Smith, 
    112 Conn. App. 592
    , 603–604, 
    963 A.2d 104
    (state’s efforts
    to find witness by visiting her home and calling her cell
    phone multiple times were sufficient to establish her
    unavailability when witness, who neither was present
    at time of shooting nor had any firsthand knowledge
    about it, testified only about victim’s demeanor prior
    to shooting), cert. denied, 
    291 Conn. 912
    , 
    969 A.2d 176
    (2009); State v. Miller, 
    56 Conn. App. 191
    , 195, 
    742 A.2d 402
    (1999) (state’s efforts to find witnesses by checking
    motor vehicle department records for their last known
    addresses and visiting those addresses prior to trial of
    defendant, who was charged with larceny and engaging
    in real estate business without license, were sufficient
    to establish witnesses’ unavailability), cert. denied, 
    252 Conn. 937
    , 
    747 A.2d 4
    (2000); the crucial nature of Parks’
    testimony and the severe crimes with which the defen-
    dant was charged ineluctably lead to the conclusion
    that the state must put forth a ‘‘greater . . . effort’’;
    Cook v. 
    McKune, supra
    , 
    323 F.3d 835
    ; to secure Parks’
    attendance at trial.15
    For the foregoing reasons, we conclude that the state
    has failed to establish that it undertook a reasonable,
    diligent, and good faith effort to locate Parks prior to
    the defendant’s trial, and, therefore, Parks’ former testi-
    mony improperly was admitted in violation of the defen-
    dant’s right of confrontation. We therefore reverse the
    judgment of the Appellate Court.
    II
    Although our conclusion in part I of this opinion that
    the defendant is entitled to a new trial disposes of this
    appeal, we address the merits of the defendant’s second
    claim that the trial court improperly admitted the testi-
    mony of the state’s expert witness on firearm and tool
    mark identification in violation of the defendant’s sixth
    amendment right of confrontation because it is likely
    to arise on remand.16 The following additional facts
    and procedural history are relevant to our review of
    this claim.
    One of the critical issues at trial was whether Barrett
    or the defendant had fired the projectile17 that fatally
    wounded the victim. The state recovered various pro-
    jectiles and casings from the scene of the crimes and
    submitted them to the state forensic laboratory for anal-
    ysis. Gerard Petillo, a former employee of the state
    forensic laboratory, examined seven of these projectiles
    and casings, produced photographs, and generated a
    ballistic report containing his expert conclusions. Ste-
    phenson, who also was employed at the state forensic
    laboratory at that time, was the ‘‘technical reviewer’’
    and ‘‘second signer’’ on Petillo’s ballistic report. As part
    of his technical review, Stephenson physically exam-
    ined four of the projectiles recovered from the scene
    of the crimes.
    Petillo died prior to trial and, therefore, was unavail-
    able to testify. The state sought to admit the in-court
    expert testimony of Stephenson in lieu of Petillo’s ballis-
    tic report. The defendant moved to suppress Stephen-
    son’s in-court testimony, contending that it was inad-
    missible under the confrontation clause of the sixth
    amendment pursuant to Bullcoming v. New Mexico,
    
    564 U.S. 647
    , 
    131 S. Ct. 2705
    , 
    180 L. Ed. 2d 610
    (2011),
    and Melendez-Diaz v. Massachusetts, 
    557 U.S. 305
    , 
    129 S. Ct. 2527
    , 
    174 L. Ed. 2d 314
    (2009), because it was
    predicated on Petillo’s ballistic report, which the defen-
    dant claimed was testimonial hearsay. The state
    opposed the defendant’s motion, arguing that, although
    Stephenson’s expert opinions ultimately were ‘‘no dif-
    ferent’’ than Petillo’s, Stephenson had formed his own
    independent conclusions after reviewing all of the infor-
    mation available, including photographs, notes, and Pet-
    illo’s report. The state argued that there was ‘‘no con-
    frontation issue’’ because the defendant would be able
    to confront Stephenson and to cross-examine him
    regarding the basis of his expert opinions. The trial
    court agreed and denied the defendant’s motion to
    suppress.
    At trial, Stephenson testified that seven nine millime-
    ter caliber cartridge cases and projectiles recovered
    from the scene of the shooting were submitted to the
    state forensic laboratory for examination. Stephenson
    explained that six of the seven cartridge cases ‘‘had
    consistent rifling characteristics as being fired [from]
    the same firearm,’’ whereas the seventh cartridge case,
    which was recovered near the victim’s body, had been
    fired from a different firearm. Similarly, with respect
    to the projectiles, Stephenson testified that one of the
    seven projectiles—the one recovered from the victim’s
    body—‘‘was inconsistent’’ and ‘‘couldn’t have come
    from the same barrel.’’ During closing argument, the
    state emphasized the importance of Stephenson’s testi-
    mony, arguing that it supported the state’s theory that
    the bullet that killed the victim ‘‘wasn’t from [Barrett’s]
    gun’’ but, rather, was from the defendant’s gun.
    On appeal, the defendant contends that the trial court
    improperly admitted Stephenson’s expert testimony in
    violation of his sixth amendment right of confrontation
    because his testimony was predicated on Petillo’s ballis-
    tic report, which he argues is testimonial hearsay, and
    the defendant did not have a prior opportunity to cross-
    examine Petillo regarding his expert conclusions. The
    state responds that the record is inadequate to review
    the defendant’s confrontation clause claim because nei-
    ther Petillo’s ballistic report nor the other materials
    ‘‘reviewed by Stephenson in preparation for his testi-
    mony were . . . marked for identification or entered
    into evidence at trial,’’ and, therefore, it cannot be deter-
    mined whether they ‘‘were, in fact, testimonial’’ in
    nature. Alternatively, the state contends that there was
    no confrontation clause violation because Stephenson
    conducted his own independent review of the evidence,
    formulated his own expert opinion, and was available
    for cross-examination. The state also argues that, even
    if a confrontation clause violation occurred, any such
    violation was harmless beyond a reasonable doubt.
    ‘‘Under Crawford v. 
    Washington, supra
    , 
    541 U.S. 59
    ,
    hearsay statements of an unavailable witness that are
    testimonial in nature may be admitted in accordance
    with the confrontation clause only if the defendant pre-
    viously has had the opportunity to cross-examine the
    unavailable witness.’’ State v. Smith, 
    289 Conn. 598
    ,
    618, 
    960 A.2d 993
    (2008). ‘‘Nontestimonial statements,
    however, are not subject to the confrontation clause
    and may be admitted under state rules of evidence.
    . . . Thus, the threshold inquiries that determine the
    nature of the claim are whether the statement was hear-
    say, and if so, whether the statement was testimonial
    in nature, questions of law over which our review is
    plenary.’’ (Citation omitted.) 
    Id., 618–19. We
    recently addressed the admissibility of expert
    testimony under the sixth amendment’s confrontation
    clause in State v. Walker, 
    332 Conn. 678
    , 
    212 A.3d 1244
    (2019). In Walker, we acknowledged that ‘‘expert wit-
    nesses . . . may base their testimony on information
    provided to them by other sources without their testi-
    mony necessarily being regarded as introducing hear-
    say.’’ 
    Id., 691; see
    also Conn. Code Evid. § 7-4 (b) (‘‘The
    facts in the particular case upon which an expert bases
    an opinion may be those perceived by or made known
    to the expert at or before the proceeding. The facts
    need not be admissible in evidence if of a type custom-
    arily relied on by experts in the particular field in form-
    ing opinions on the subject.’’). ‘‘Accordingly, [w]hen the
    expert witness has consulted numerous sources, and
    uses that information, together with his own profes-
    sional knowledge and experience, to arrive at his opin-
    ion, that opinion is regarded as evidence in its own
    right and not as hearsay in disguise.’’ (Emphasis in
    original; internal quotation marks omitted.) State v.
    
    Walker, supra
    , 692.
    ‘‘Nonetheless, the underlying information upon
    which the expert’s opinion is based may not itself be
    admitted into evidence for its truth.’’ Id.; see also Conn.
    Code Evid. § 7-4 (b) (‘‘[t]he facts relied on [by the
    expert] pursuant to this subsection are not substantive
    evidence, unless otherwise admissible as such evi-
    dence’’). ‘‘Accordingly, the testimony of an expert wit-
    ness improperly introduces hearsay when the out-of-
    court statements upon which it is based are themselves
    admitted into evidence to prove the truth of what they
    assert.’’ State v. 
    Walker, supra
    , 
    332 Conn. 692
    .
    ‘‘In criminal cases, the admission of expert testimony
    that is based upon an out-of-court statement may impli-
    cate the confrontation clause if the underlying state-
    ment itself is testimonial. Acknowledging these con-
    cerns, courts have held that expert witnesses may base
    their opinions on the testimonial findings of other
    experts without violating the confrontation clause if
    those underlying findings are not themselves put before
    the jury. . . . On the other hand, where the testifying
    expert explicitly refers to, relies on, or vouches for the
    accuracy of the other expert’s findings, the testifying
    expert has introduced out-of-court statements that, if
    offered for their truth and are testimonial in nature, are
    subject to the confrontation clause.’’ (Citations omit-
    ted.) 
    Id., 693–94. Thus,
    expert testimony is inadmissible
    under the confrontation clause if it is ‘‘used as [a con-
    duit] for the admission into evidence of the testimonial
    statements of others.’’ 
    Id., 695. We
    applied these principles in Walker to determine
    whether the admission into evidence of the testimony
    and report of the state’s expert witness on DNA,
    Heather Degnan, violated the sixth amendment right of
    confrontation of the defendant, Eugene L. Walker. 
    Id., 680–81. Degnan
    personally tested a bandana found at
    the scene of the crime and determined that it contained
    Walker’s DNA, but her expert opinion was predicated
    on a DNA profile for Walker generated, without her
    participation, by the ‘‘ ‘known processing group.’ ’’ 
    Id., 684. Specifically,
    an analyst or analysts at the known
    processing group had analyzed Walker’s buccal swab
    and generated a ‘‘known’’ DNA profile for Walker, which
    Degnan then relied on to reach her conclusion that the
    DNA found on the bandana belonged to Walker. 
    Id. Degnan ‘‘neither
    performed nor observed the analysis
    of the buccal swab that produced [Walker’s] DNA pro-
    file’’; 
    id., 681; nor
    was there any evidence that she was
    provided with ‘‘the raw machine data . . . .’’ 
    Id., 696. Nonetheless,
    at the defendant’s trial, Degnan swore ‘‘ ‘to
    the accuracy’ of the DNA profile provided to her’’ and
    testified ‘‘that the analyst or analysts who processed
    the known samples ‘did it properly, followed standard
    operating procedures.’ ’’ 
    Id., 685–86. We
    concluded in Walker that ‘‘Degnan’s testimony at
    trial necessarily introduced the out-of-court statements
    of the known processing group and did not consist
    merely of her own independent opinion.’’ 
    Id., 697. Although
    ‘‘Degnan’s testimony about the DNA profiles
    she generated from the bandana was not hearsay
    because she conducted these analyses herself,’’ Degnan
    ‘‘explicitly referred to, relied on, and vouched for the
    quality of work that she did not perform and, in so
    doing, relayed to the jury the known processing group’s
    out-of-court statements about [Walker’s] numerical
    DNA profile.’’ 
    Id. Additionally, ‘‘Degnan
    introduced the
    known processing group’s out-of-court statements by
    including in her report, which was admitted into evi-
    dence without limitation, the allele numbers comprising
    [Walker’s] DNA profile that the known processing group
    had provided to her.’’ 
    Id., 697–98. Because
    the known
    processing group’s out-of-court statement regarding
    Walker’s DNA profile was offered for its truth, was
    hearsay, and was testimonial in nature; 
    id., 700; we
    held that Degnan’s expert testimony was admitted in
    violation of Walker’s sixth amendment right of confron-
    tation. 
    Id., 719–20. Pursuant
    to Walker, Stephenson’s testimony was
    admissible, even if predicated in material part on testi-
    monial hearsay, as long as the underlying hearsay was
    not admitted into evidence or otherwise put before the
    jury for the truth of the matter asserted. The record
    reflects that neither Petillo’s ballistic report nor any of
    the statements or conclusions contained therein were
    admitted into evidence, either as an exhibit or through
    the conduit of Stephenson’s live, in-court testimony.
    Although the jury was informed that Stephenson had
    reviewed ‘‘a number of reports and photographs in prep-
    aration for [his] testimony,’’ the contents of those
    reports were not presented to the jury. When the state
    attempted to elicit information regarding ‘‘which
    reports [Stephenson had] reviewed,’’ the defendant
    objected to this line of inquiry, and the trial court implic-
    itly sustained the defendant’s objection, ruling that Ste-
    phenson’s testimony must be limited ‘‘to his own con-
    clusions.’’ Thus, the jury was not informed of the nature
    of the reports on which Stephenson had relied, who
    generated the reports, what information they contained,
    or whether Stephenson’s expert opinions were consis-
    tent with the reports. On the record before us, we con-
    clude that Stephenson applied ‘‘his training and experi-
    ence to the sources before him and reach[ed] an
    independent judgment,’’ the basis of which could be
    ‘‘tested through cross-examination.’’18 United States v.
    Johnson, 
    587 F.3d 625
    , 635 (4th Cir. 2009), cert. denied
    sub nom. Martin v. United States, 
    559 U.S. 1082
    , 
    130 S. Ct. 2128
    , 
    176 L. Ed. 2d 749
    (2010). ‘‘Where, as here,
    expert witnesses present their own independent judg-
    ments, rather than merely transmitting testimonial hear-
    say, and are then subject to cross-examination, there
    is no [c]onfrontation [c]lause violation.’’ 
    Id., 636; see
    also Bullcoming v. New 
    Mexico, supra
    , 
    564 U.S. 673
    (Sotomayor, J., concurring in part) (concluding that
    admission of expert report violated confrontation
    clause but noting that ‘‘[w]e would face a different ques-
    tion if asked to determine the constitutionality of
    allowing an expert witness to discuss others’ testimo-
    nial statements if the testimonial statements were not
    themselves admitted as evidence’’); United States v.
    Mejia, 
    545 F.3d 179
    , 198 (2d Cir. 2008) (‘‘the question
    under Crawford is whether the expert applied his exper-
    tise to those [testimonial] statements but did not
    directly convey the substance of the statements to the
    jury’’ [internal quotation marks omitted]); State v.
    McLeod, 
    165 N.H. 42
    , 53, 
    66 A.3d 1221
    (2013) (‘‘the
    [c]onfrontation [c]lause is not violated when an expert
    testifies regarding his or her independent judgment,
    even if that judgment is based [on] inadmissible testimo-
    nial hearsay’’); State v. Griep, 
    361 Wis. 2d 657
    , 682–83,
    
    863 N.W.2d 567
    (2015) (no confrontation clause viola-
    tion when nontestifying analyst’s ‘‘testimonial forensic
    report is not admitted and the expert witness who testi-
    fies at trial gives his or her independent opinion after
    review of laboratory data’’), cert. denied,     U.S.    ,
    
    136 S. Ct. 793
    , 
    193 L. Ed. 2d 709
    (2016).
    The judgment of the Appellate Court is reversed and
    the case is remanded to that court with direction to
    remand the case to the trial court for a new trial.
    In this opinion PALMER, McDONALD and D’AURIA,
    Js., concurred.
    1
    The confrontation clause of the sixth amendment to the United States
    constitution, which is applicable to the states through the due process clause
    of the fourteenth amendment; Pointer v. Texas, 
    380 U.S. 400
    , 403, 
    85 S. Ct. 1065
    , 
    13 L. Ed. 2d 923
    (1965); provides in relevant part that, ‘‘[i]n all criminal
    prosecutions, the accused shall enjoy the right . . . to be confronted with
    the witnesses against him . . . .’’ U.S. Const., amend. VI.
    2
    Section 8-6 of the Connecticut Code of Evidence provides in relevant
    part: ‘‘The following are not excluded by the hearsay rule if the declarant
    is unavailable as a witness:
    ‘‘(1) Former testimony. Testimony given as a witness at another hearing
    of the same or a different proceeding, provided (A) the issues in the former
    hearing are the same or substantially similar to those in the hearing in which
    the testimony is being offered, and (B) the party against whom the testimony
    is now offered had an opportunity to develop the testimony in the former
    hearing. . . .’’
    3
    The trial court vacated the jury’s findings of guilty with respect to the
    charges of conspiracy to commit burglary in the first degree in violation of
    §§ 53a-48 (a) and 53a-101 (a) (1) and conspiracy to commit robbery in the
    first degree in violation of §§ 53a-48 (a) and 53a-134 (a) (2) because ‘‘[t]here
    can . . . be [only] one conspiracy.’’
    4
    The defendant also challenged the admission of Stephenson’s expert
    testimony under § 4-1 of the Connecticut Code of Evidence, arguing that
    ‘‘the state failed to establish the relevancy of Stephenson’s testimony by
    providing a sufficient evidentiary foundation that the photographs, report,
    and notes relied on by Stephenson were associated with the crimes at issue
    in this case.’’ State v. 
    Lebrick, supra
    , 
    179 Conn. App. 239
    . The Appellate
    Court declined to address that claim because it was not preserved in the
    trial court. 
    Id., 240. The
    defendant has abandoned the claim in this certified
    appeal. Although we reverse the Appellate court’s judgment insofar as it
    affirmed the judgment of conviction, we take no position concerning the
    Appellate Court’s analysis with respect to this issue.
    5
    We granted the defendant’s petition for certification, limited to the follow-
    ing issues: (1) ‘‘Did the Appellate Court properly conclude that the trial
    court properly admitted the probable cause hearing testimony of . . .
    Parks?’’ And (2) ‘‘[d]id the Appellate Court properly conclude that the trial
    court properly admitted the testimony of . . . Stephenson?’’ State v.
    Lebrick, 
    328 Conn. 912
    , 
    179 A.3d 218
    (2018).
    6
    The evidence at trial established that the van was owned by Jamie
    Henlon, who had rented it to the defendant.
    7
    At the defendant’s trial, Emory L. Hightower, the inspector in the Hartford
    state’s attorney’s office assigned to locate Parks, testified on October 27,
    2014, that he had commenced his search for Parks ‘‘approximately two
    months ago.’’
    8
    Although the trial court did not make any explicit factual findings, its
    ruling necessarily included an implicit finding that the state’s efforts to
    produce Parks’ attendance at trial were reasonable, diligent, and conducted
    in good faith. See, e.g., State v. Azukas, 
    278 Conn. 267
    , 276, 
    897 A.2d 554
    (2006) (holding that trial court’s ruling on motion to suppress ‘‘necessarily
    included an implicit finding’’ on whether homeowner had authority to con-
    sent to search of bedroom that his daughter shared with defendant); State
    v. Johnson, 
    253 Conn. 1
    , 25, 
    751 A.2d 298
    (2000) (holding that, ‘‘in accepting
    the defendant’s guilty plea, the trial court implicitly found him [to be] com-
    petent’’).
    9
    We recognize that the federal habeas cases cited here are subject to the
    Antiterrorism and Effective Death Penalty Act of 1996, 28 U.S.C. § 2254,
    which requires federal courts to apply a presumption of correctness to a
    state court’s factual findings. See 28 U.S.C. § 2254 (e) (1) (2012) (‘‘a factual
    issue made by a [s]tate court shall be presumed to be correct’’). Nonetheless,
    we conclude that the ‘‘mixed question of law and fact’’ standard appropriately
    balances the traditional deference afforded to a trial court’s factual findings
    and the plenary review of a trial court’s ultimate legal determination regard-
    ing the existence of a constitutional violation.
    10
    The defendant does not challenge, as a factual matter, the efforts under-
    taken by Hightower and Garguilo to locate Parks prior to trial. Rather, his
    claim is that these efforts were insufficient as a matter of law to establish
    Parks’ unavailability.
    11
    In doing so, we do not intend to suggest that other factors relevant to
    the reasonableness inquiry cannot be considered in any particular case.
    12
    The state conceded at oral argument that, if Parks’ former testimony
    improperly was admitted in violation of our rules of evidence or the confron-
    tation clause, then the improper admission cannot be deemed harmless.
    13
    Barrett was unable to identify the defendant as the individual who shot
    him and killed the victim. Although Ricky Naylor, the defendant’s former
    cellmate at the MacDougall-Walker Correctional Institution, testified at trial
    that the defendant had admitted to him that he was involved in a ‘‘robbery
    gone bad,’’ he was armed with a gun, and three people died, Naylor’s testi-
    mony differed from Parks’ because, according to Naylor, the defendant did
    not take the gun away from the victim, but, rather, his ‘‘cousins gave him
    a gun’’ before he entered the apartment. Furthermore, unlike Parks, Naylor
    did not testify that the defendant admitted to firing his weapon or shooting
    his way out of the apartment. Therefore, we agree with the state that Parks’
    testimony contained key inculpatory facts not available through the testi-
    mony of any other witness.
    14
    We disagree with the dissenting opinion that the evidence supports a
    reasonable inference that Hightower used a ‘‘nonbasic’’ subscription to
    CLEAR to search for Parks. Although Hightower at one point testified that
    he thought that CLEAR included ‘‘all public databanks . . . or any sort of
    anything that has to do with a public domain,’’ he later admitted that he
    did not ‘‘know [the] specifics’’ of ‘‘how extensive’’ their databases are and
    the types of information available. Tiernam, the CLEAR product specialist,
    testified that CLEAR searches ‘‘detailed reports like . . . lawsuits, liens,
    [and] judgments’’ or ‘‘social media information’’ only if the subscriber pur-
    chases an enhanced subscription. There is no evidence in the record, much
    less the substantial evidence required to meet the state’s burden, to support
    a reasonable inference that ‘‘the state . . . opted for the higher level sub-
    scription to CLEAR,’’ as the dissent posits. The trial court itself made no such
    finding. To the contrary, our review of the record compels the conclusion
    that Hightower’s CLEAR search encompassed only basic location informa-
    tion. See State v. 
    Mangual, supra
    , 
    311 Conn. 197
    (when defendant’s constitu-
    tional rights are at stake, reviewing court must ‘‘conduct a scrupulous exami-
    nation of the record . . . in order to ascertain whether, in light of the totality
    of the circumstances, the trial court’s finding is supported by substantial
    evidence’’ [internal quotation marks omitted]).
    15
    Our conclusion is not predicated on ‘‘twenty-twenty hindsight,’’ as the
    dissenting opinion suggests. Hindsight has no role in our analysis. Our
    conclusion is based instead on the facts and circumstances known or readily
    knowable to Hightower when he conducted his search. Hightower knew
    that Parks was a reluctant witness who resided in the state of New York,
    yet he never searched any New York state governmental databases, including
    its motor vehicle, family court, child support, or housing records. Hightower
    delegated the actual physical effort to serve process on Parks in New York
    entirely to Garguilo, but he never even spoke with Garguilo regarding the
    assignment and did not ask him to conduct any actual investigative work.
    When Hightower thereafter received word that Garguilo’s efforts to serve
    Parks were unsuccessful, Hightower did not pursue any follow-up, for exam-
    ple, by asking Garguilo to return to the locations at a time outside of normal
    working hours. Hightower also failed to conduct basic Internet searches.
    It was common knowledge in 2014, as it is today, that publicly available
    websites such as Google and Facebook are valuable resources for locating
    individuals, and these resources were (and continue to be) used every day
    by tens of millions of people to locate everything and everyone from the
    nearest gas station to a long lost childhood friend. Yet Hightower did not
    use these tools to search for Parks. It is unknown whether any of these
    inquiries would have unearthed information leading to Parks’ whereabouts,
    but it is not the defendant’s burden to demonstrate that Hightower’s efforts
    would have been successful. Instead, it is the state’s burden to demonstrate
    that Hightower’s efforts were reasonable under the circumstances. See, e.g.,
    Ohio v. 
    Roberts, supra
    , 
    448 U.S. 74
    –75 (under confrontation clause, ‘‘the
    prosecution bears the burden of establishing’’ that ‘‘the witness is unavailable
    despite [good faith] efforts undertaken prior to trial to locate and present
    that witness’’). It is not hindsight to observe that numerous basic and obvious
    avenues of inquiry were left unpursued. Simply put, the state has failed to
    meet its burden of demonstrating that Hightower’s efforts were reasonable
    in this case.
    16
    ‘‘Ordinarily, we do not decide constitutional issues when resolving those
    issues is not necessary to dispose of the case before us. . . . We have
    made an exception to this rule, however, when an issue with constitutional
    implications that has been presented and briefed by the parties is likely to
    arise on remand.’’ In re Taijha H.-B., 
    333 Conn. 297
    , 312 n.9, 
    216 A.3d 601
    (2019).
    17
    Stephenson explained that a projectile is a bullet that exits the cartridge
    case of the firearm during the firing process, leaving behind a casing.
    18
    The defendant claims that Stephenson’s expert testimony is inadmissible
    pursuant to State v. Buckland, 
    313 Conn. 205
    , 
    96 A.3d 1163
    (2014), cert.
    denied, 
    574 U.S. 1078
    , 
    135 S. Ct. 992
    , 
    190 L. Ed. 2d 837
    (2015), because
    the state failed to produce the live in-court testimony of ‘‘the person who
    performed the test . . . .’’ We disagree. In Buckland, the defendant claimed
    that the results of his breath alcohol test improperly were admitted under
    the confrontation clause because ‘‘the state did not produce four witnesses
    regarding the [Breathalyzer] machine and its calibration . . . .’’ 
    Id., 211. We
    rejected the defendant’s claim because, among other reasons, the ‘‘live
    presence’’ of ‘‘both the person who performed the test . . . and an expert
    to explain the results’’ satisfied the requirements of the confrontation clause.
    
    Id., 216. Buckland
    is distinguishable from the present case because Stephen-
    son did not explain the results of a test performed by an out-of-court declar-
    ant; instead, he testified about the results of his own independent analysis
    of the available information. Accordingly, the defendant’s reliance on Buck-
    land is misplaced.