United States v. Oscar Rodriguez ( 2014 )


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  •                 FOR PUBLICATION
    UNITED STATES COURT OF APPEALS
    FOR THE NINTH CIRCUIT
    UNITED STATES OF AMERICA,             No. 08-50479
    Plaintiff-Appellee,
    D.C. No.
    v.                    5:05-cr-00069-
    VAP-3
    OSCAR RODRIGUEZ, AKA Lonely,
    Defendant-Appellant.
    UNITED STATES OF AMERICA,             No. 08-50483
    Plaintiff-Appellee,
    D.C. No.
    v.                    5:05-cr-00069-
    VAP-2
    JOSE MURILLO, AKA Yogi,
    Defendant-Appellant.
    UNITED STATES OF AMERICA,             No. 08-50485
    Plaintiff-Appellee,
    D.C. No.
    v.                    5:05-cr-00069-
    VAP-4
    ALEJANDRO MUJICA, AKA Slow,
    Defendant-Appellant.
    2                UNITED STATES V. RODRIGUEZ
    UNITED STATES OF AMERICA,                         No. 12-50121
    Plaintiff-Appellee,
    D.C. No.
    v.                           5:05-cr-00069-
    VAP-3
    OSCAR RODRIGUEZ, AKA Lonely,
    Defendant-Appellant.
    UNITED STATES OF AMERICA,                         No. 12-50132
    Plaintiff-Appellee,
    D.C. No.
    v.                           5:05-cr-00069-
    VAP-2
    JOSE MURILLO, AKA Yogi,
    Defendant-Appellant.                   OPINION
    Appeal from the United States District Court
    for the Central District of California
    Virginia A. Phillips, District Judge, Presiding
    Argued and Submitted
    August 28, 2013—Pasadena, California
    Filed June 19, 2014
    Before: Ronald M. Gould and Johnnie B. Rawlinson,
    Circuit Judges, and Ivan L.R. Lemelle, District Judge.*
    Opinion by Judge Rawlinson
    *
    The Honorable Ivan L.R. Lemelle, U.S. District Judge for the Eastern
    District of Louisiana, sitting by designation.
    UNITED STATES V. RODRIGUEZ                            3
    SUMMARY**
    Criminal Law
    The panel affirmed three defendants’ convictions for
    conspiracy to commit murder and first degree murder
    stemming from the stabbing of a prison inmate, Peter
    Scopazzi.
    The panel held that the district court’s exclusion of
    evidence concerning medical negligence and Scopazzi’s
    removal of his breathing tube does not warrant reversal of the
    convictions, where the defendants failed to demonstrate that
    any medical negligence related to Scopazzi’s multiple stab
    wounds and his removal of his breathing tube were the sole
    causes of his death or were so extraordinary and
    unforeseeable as to absolve the defendants of liability for
    their vicious assault.
    The panel held that the district court did not abuse its
    discretion in admitting evidence of the defendants’
    connections to the Mexican Mafia to demonstrate their
    motive for murdering Scopazzi. The panel also held that
    expert testimony concerning the connections between the
    Sureños and the Mexican Mafia within the prison gang
    hierarchy and photographs of the defendants with Mexican
    Mafia members did not render their trial unfair because the
    district court properly minimized any prejudice stemming
    from the evidence and the trial was replete with admissible
    evidence regarding the defendants’ gang affiliations.
    **
    This summary constitutes no part of the opinion of the court. It has
    been prepared by court staff for the convenience of the reader.
    4              UNITED STATES V. RODRIGUEZ
    The panel held that the defendants failed to demonstrate
    under Brady, Mooney, or Napue that a new trial was
    warranted based on the government’s failure to disclose
    immaterial information regarding a government witness’
    sentence reduction and his cooperation in a DEA
    investigation.
    COUNSEL
    Verna Wefald (argued), Pasadena, California, for Defendant-
    Appellant Oscar Rodriguez.
    Michael J. Treman, Santa Barbara, California, for Defendant-
    Appellant Jose Murillo.
    Ethan A. Balogh (argued) and Jay A. Nelson, Coleman &
    Balogh LLP, San Francisco, California, for Defendant-
    Appellant Alejandro Mujica.
    André Birotte, Jr., United States Attorney, Robert E. Dugdale,
    Chief Assistant United States Attorney, Antoine F. Raphael
    (argued), Assistant United States Attorney, Riverside,
    California, for Plaintiff-Appellee United States.
    OPINION
    RAWLINSON, Circuit Judge:
    Appellants Oscar Rodriguez (Rodriguez), Jose Murillo
    (Murillo), and Alejandro Mujica (Mujica) challenge their
    convictions for conspiracy to commit murder and first degree
    murder stemming from the stabbing of a prison inmate, Peter
    UNITED STATES V. RODRIGUEZ                     5
    Scopazzi (Scopazzi) at the United States Penitentiary at
    Victorville, California. Appellants contend that the district
    court abused its discretion in excluding evidence that medical
    negligence and Scopazzi’s removal of his breathing tube
    during his hospitalization may have been the proximate cause
    of Scopazzi’s death. Appellants also argue that the district
    court abused its discretion in admitting expert testimony
    concerning the relationship between two prison gangs – the
    Sureños and the Mexican Mafia – because Appellants were
    not members of the Mexican Mafia.
    Additionally, Appellants maintain that a new trial was
    warranted because the government failed to disclose, as
    required by Brady v. Maryland, 
    373 U.S. 83
    (1963) and
    Giglio v. United States, 
    405 U.S. 150
    (1972), a tacit
    agreement with a key government witness that the
    government would seek a sentence reduction in exchange for
    the witness’s favorable testimony, and that the witness was an
    informant for the Drug Enforcement Administration (DEA).
    Appellants further assert that the government violated
    Mooney v. Holohan, 
    294 U.S. 103
    (1935) and Napue v.
    Illinois, 
    360 U.S. 264
    (1959), by allowing the witness to
    falsely testify that there was no promise of a sentence
    reduction based on the witness’s cooperation. We affirm
    Appellants’ convictions and the district court’s denial of their
    motion for a new trial.
    I. BACKGROUND
    In a second superseding indictment, Appellants, along
    with Danny Martinez (Martinez) and Walter Meneses
    (Meneses), were charged with “knowingly and willfully
    conspir[ing] and agree[ing] with each other to murder inmate
    David Fischer . . . aka Peter Scopazzi” in violation of
    6                 UNITED STATES V. RODRIGUEZ
    18 U.S.C. § 1111. The indictment alleged that Appellants
    armed themselves with prison-made knives (shanks) and
    murdered Scopazzi in his cell. Appellants were charged with
    “willfully, deliberately, and with premeditation and malice
    aforethought, unlawfully kill[ing] [Scopazzi].” Appellants
    were also charged with assaulting two other prison inmates,
    Timothy Ultsch (Ultsch) and Wayne Rondeau (Rondeau),
    with the intent to commit murder and assault with a deadly
    weapon “with the intent to do bodily harm.”
    Prior to trial, the government filed a motion in limine to
    exclude evidence that medical negligence may have
    contributed to Scopazzi’s death. The government maintained
    that Appellants “proffered no witness, expert or otherwise,
    nor any other evidence to the government that would indicate
    that [Scopazzi’s] treatment by medical staff was somehow
    negligent. . . .” The government also asserted that such
    evidence was irrelevant because Appellants were liable for
    murder irrespective of any medical negligence and that the
    evidence might lead to juror confusion.
    The government also filed a related motion in limine to
    preclude or limit the testimony of the defense’s medical
    expert, Dr. Marshall Morgan, concerning medical
    negligence.1 The government asserted that the defense’s
    1
    In a letter to the prosecution, Murillo’s attorney stated that the defense
    intended to call Dr. Morgan to “testify about the nature of the stab wounds
    suffered by [Scopazzi] . . . and the medical care given to [Scopazzi] by
    prison and hospital personnel to treat those injuries.” “He will state that
    in his opinion [Scopazzi’s] stab wounds could have been successfully
    treated surgically. Furthermore, if [Scopazzi’s] condition had been
    properly evaluated, the need for immediate surgery should have been
    obvious.” “But because the nature of [Scopazzi’s] injuries was not
    promptly or competently assessed and appropriately treated, the medical
    UNITED STATES V. RODRIGUEZ                             7
    notice did “not indicate that Dr. Morgan will state that
    [Scopazzi’s] death was caused solely by the independent
    intervening acts of the medical staff’s treatment. That
    [Scopazzi’s] life may have been saved by more skillful
    medical treatment, even if true, is legally irrelevant . . .
    because even if this were true it would not relieve defendants
    of responsibility for [Scopazzi’s] murder. . . .”
    In his oppositions to the government’s motions, Murillo
    responded that he did “not intend to introduce evidence of
    negligence as an affirmative defense to murder. . . .” Murillo
    maintained that the evidence of medical negligence and Dr.
    Morgan’s testimony “would further explain that the injuries
    caused by the stab wounds would have been routinely
    repaired with proper medical care. The nature of [Scopazzi’s]
    wounds and degree of force used to cause them may be
    circumstantial evidence of whether or not there was intent to
    kill. . . .”
    In granting the government’s motions, the district court
    held that medical negligence was not a defense to murder
    charges. The district court excluded Dr. Morgan’s testimony
    because Murillo failed “to proffer expert testimony that
    [Scopazzi’s] death was caused solely by the independent
    intervening acts of the medical staff’s treatment. . . .” The
    district court held that “Dr. Morgan shall be allowed to testify
    regarding the nature of [Scopazzi’s] wounds and the degree
    of force used to cause them as such testimony is relevant to
    the intent of the Defendants. . . .” However, Dr. Morgan was
    precluded from testifying “about medical negligence in this
    attention he did receive fell well below well-recognized standards of care
    resulting in [Scopazzi’s] death.”
    8               UNITED STATES V. RODRIGUEZ
    case as the probative value of such evidence outweighs the
    danger of confusing the jury.”2
    In its trial memorandum, the government sought to
    introduce evidence that the motive for Appellants’ murder of
    Scopazzi was Scopazzi’s disrespect of Sureños gang
    members. The district court held that evidence of Appellants’
    Sureños membership and the Sureños’ relationship with the
    Mexican Mafia was admissible as relevant to the
    government’s theory that Appellants assaulted Scopazzi due
    to their Mexican Mafia connections. The district court held
    that the gang affiliation evidence was more probative than
    prejudicial and that the government was permitted to
    introduce “a limited number of photographs of [Appellants]
    posing with certain members of the Mexican Mafia, as such
    evidence may go to issues of planning and preparation of the
    alleged offenses, and the level of retribution called for under
    the tenets of the Sureños. . . .” Appellants declined the
    district court’s offer to provide a limiting instruction
    concerning evidence related to the Mexican Mafia.
    At trial, Ryan Davis (Davis), a former Victorville inmate
    imprisoned for being a felon in possession of a firearm and an
    armed career criminal, testified that he had prior convictions
    for burglary, providing false information to a police officer,
    attempting to [elude] a police officer and reckless driving,
    unlawful delivery of a controlled substance, and criminal
    mischief. While in prison, Davis “used marijuana, meth and
    heroin and drank,” and was involved in an attack on another
    inmate.
    2
    The judge apparently meant to say that the probative value of the
    evidence was outweighed by the danger of confusing the jury.
    UNITED STATES V. RODRIGUEZ                          9
    According to Davis, he was not a gang member, but was
    affiliated with the Aryan Brotherhood and Nazi Low Riders
    and had several tattoos including swastikas and the phrase
    “white power” on his chest. Despite his lack of gang
    membership, Davis was “handed the keys for unit 4A,” a
    prison housing unit. Davis was given this leadership position
    by a member of the Aryan Brotherhood. Davis related that he
    became the unit’s key holder because there were no gang
    members in the unit capable of the position.
    According to Davis, Rodriguez belonged to the Sureños
    and answered to the Mexican Mafia. Davis related that the
    Sureños and the white inmates generally got along well and
    “called each other comrades.” Davis got along well with
    Rodriguez and the other Sureños. Davis testified that inmates
    would have to receive permission to assault members of
    another race “from the top person for their race on the yard.”
    Otherwise, “their race would stab them in return.”
    On April 11, 2005, Davis noticed that Scopazzi, Ultsch,
    and Rondeau had been drinking. Davis observed that
    Scopazzi was still drinking during dinner. Davis had injected
    methamphetamine on that day.
    Later, Davis noticed Murillo, Rodriguez, and Mujica with
    another inmate, Dan Petty (Petty), in the prison yard.3
    According to Davis, Petty was escorting Murillo, Rodriguez,
    and Mujica through the yard so that they would not be
    stopped by the guards. Davis related that it was common
    practice for an inmate to escort other inmates who had
    3
    During his testimony, Davis refers to Murillo, Rodriguez, and Mujica
    by their nicknames Yogi for Murillo, Lonely for Rodriguez, and Slow for
    Mujica. This opinion refers to Appellants by their last names.
    10             UNITED STATES V. RODRIGUEZ
    weapons, alcohol, or drugs so as to create a diversion if
    stopped by the guards.
    Davis subsequently met Scopazzi on the yard. Scopazzi
    “was drunk, kind of hyperactive. He was shadow boxing . . .
    with [Rondeau].” Murillo, Rodriguez, and Mujica “walked
    up while [Scopazzi] was horse playing” and looked irritated.
    Davis decided that he needed to “get [Scopazzi, Rondeau and
    Ultsch] to go to bed, to go to sleep so that . . . hopefully
    nothing would happen over in their side of the unit.”
    After Davis took Scopazzi and Ultsch to their cell, Robert
    Salazar (Salazar) visited the cell and inquired if there were
    any problems between Scopazzi and Murillo. Scopazzi joked
    that he and Murillo could “go in the TV room,” meaning that
    Scopazzi and Murillo could fight. Davis told Salazar that
    Scopazzi was “acting up, but everything’s all right . . .”
    Salazar responded, “all right guys” and “left the cell.” Davis
    believed that Salazar “obviously was sizing stuff up.” After
    Salazar left, Scopazzi told Davis that another inmate had
    Scopazzi’s shank in the television room and Davis instructed
    Rondeau to retrieve the shank.
    Murillo, Rodriguez, and Mujica entered Scopazzi’s cell
    and closed the door behind them. Murillo went to the corner
    of the cell with his hands under his shirt. According to Davis,
    Murillo “had his teeth locked and his jaw clenched and his
    eyes were focused on [Scopazzi], and he just had a real angry
    look . . .” Davis told Murillo that Scopazzi had been drinking
    and pleaded with Murillo, “Don’t do this.” Murillo warned
    Davis to back up or he would “get stabbed, too.” Davis
    noticed a piece of white sheet in Murillo’s hand, which was
    “common with shanks. Davis also observed a bandana
    wrapped around Mujica’s hand as Mujica moved towards
    UNITED STATES V. RODRIGUEZ                   11
    Scopazzi. As Davis grabbed Mujica and pulled him to the
    floor, Murillo stabbed Scopazzi. Rodriguez also had a shank
    and stabbed Rondeau in the face. Davis noticed that
    Rodriguez had gloves on his hands. When Ultsch returned to
    the cell, he was stabbed by Rodriguez. According to Davis,
    Scopazzi did not make any threatening moves or statements
    prior to the altercation. Davis testified that he never learned
    why Murillo, Rodriguez, and Mujica attacked Scopazzi.
    After the altercation, Davis assisted Scopazzi, who had
    “puncture wounds in his chest.” Although Scopazzi told
    Davis that he was all right, Davis was concerned about
    Scopazzi’s breathing. Because Davis thought Scopazzi had
    a punctured lung, he assisted Scopazzi in seeking medical
    treatment. When Scopazzi continued to refuse medical
    treatment, prison guards placed him on the ground and
    shackled him.
    Davis subsequently saw Salazar in the Special Housing
    Unit’s recreation area, and Salazar told Davis to inform the
    FBI that Scopazzi had a knife. Davis eventually provided a
    statement to the FBI and was placed in protective custody.
    Davis acknowledged that termination of his sentence was
    possible based on his cooperation. Davis also conceded that
    he may have received a sentence reduction and been placed
    in a safer environment due to his cooperation. Davis
    acknowledged that he signed a letter agreement with the
    government requiring Davis to testify truthfully. According
    to Davis, the letter agreement did not contain any promises
    concerning a sentence reduction, and any leniency was not
    contingent upon the trial’s outcome.
    Regarding Davis’ testimony, the district court instructed
    the jury that Davis “may have received, or may receive,
    12             UNITED STATES V. RODRIGUEZ
    benefits from the government in connection with this case.
    For this reason, in evaluating the testimony . . . [the jury]
    should consider the extent to which or whether that witness’s
    testimony may have been influenced by this factor. In
    addition, [the jury] should examine [Davis’] testimony with
    greater caution than that of other witnesses.”
    Dr. Glenn Holt, a medical examiner for San Bernardino
    County, performed the autopsy on Scopazzi. Dr. Holt
    observed that there were five puncture wounds on Scopazzi’s
    body. The first puncture wound was approximately three
    inches deep and “went through the skin, soft tissue, and
    muscle and hit the third rib and caused some hemorrhage
    above and below the third rib and also in the muscle between
    the third and fourth ribs. . . .” The second puncture wound
    was “a little over three inches” deep and penetrated
    Scopazzi’s right lung, causing the lung to collapse. The third
    puncture wound was approximately five inches deep and
    entered the peritoneal cavity creating a hole in the liver. The
    fourth puncture wound was approximately “two and a third
    inches” deep and penetrated the muscle wall into the
    peritoneal cavity. The fifth puncture wound was “a third of
    an inch” deep in Scopazzi’s right upper arm.
    Dr. Holt opined that the cause of Scopazzi’s death was a
    “sequelae of puncture wounds of torso” and “the sequelae
    [were] events following an initial event, so . . . the injuries
    occur and during events subsequently there were
    complications that led to his death.” Dr. Holt related that
    “there were some complications that flowed from the fact that
    UNITED STATES V. RODRIGUEZ                           13
    [Scopazzi] was stabbed” and that those complications led to
    his death.4
    Officer Robert Riley, a Bureau of Prisons correctional
    officer, testified that he was working at the Special Housing
    Unit in April, 2005. On April 14, 2005, Officer Riley
    searched Murillo’s cell and found a small note referred to as
    a “kite” in “a baby powder bottle.” According to a stipulated
    translation of the kite, Murillo stated that Scopazzi had
    “disrespected the ‘Sur,’” that Scopazzi and the other inmates
    “got what they had coming, cause [sic] I’m 100% Rider
    homeboy. . . .”
    Special Agent Daniel Evanilla of the California
    Department of Corrections and Rehabilitation testified as an
    expert on prison gangs. According to Agent Evanilla,
    “Sureños are Hispanic gang members that, when they go to a
    prison or a county jail, band together as a group. . . .” Agent
    Evanilla related that “the Sureños are the recruitment pool for
    the Mexican Mafia,” and “[t]hey are considered the foot
    soldiers for the Mexican Mafia.” “The Sureños conduct
    criminal activities for the Mexican Mafia prison gang. They
    respond to . . . the edicts and the orders of the Mexican Mafia
    prison gang in terms of their criminal activities, their rules,
    their regulations and how they conduct themselves in prison.”
    Agent Evanilla testified that respect from other prisoners was
    an important element of the Sureños’ credo and disrespect
    was “not tolerated.” Disrespect from a member of another
    race, particularly when witnessed by other Sureños, was “a
    major factor” in the Sureños’ culture. According to Agent
    4
    During cross-examination, the district court sustained objections to the
    defense’s questions concerning the specific complications that led to
    Scopazzi’s death and whether brain swelling was the major complication.
    14             UNITED STATES V. RODRIGUEZ
    Evanilla, the reprisal for such disrespect would be “[s]ome
    violent assault.” Agent Evanilla reviewed the kite that was
    discovered by prison officials in Murillo’s cell and
    interpreted the kite as meaning that the white inmates had
    disrespected the Sureños.
    Captain Robert Hodak of the Englewood Federal
    Correctional Institution also testified that the Sureños were
    “the foot soldiers for the Mexican Mafia.” According to
    Captain Hodak, Salazar was an influential member of the
    Sureños and was considered a “[comrade] of the Mexican
    Mafia.” Captain Hodak investigated the assault on Scopazzi.
    After reviewing the video of the inmates prior to the assault,
    Captain Hodak opined that, based on demeanor, positioning,
    and body language, Meneses and Martinez served as
    lookouts.
    Salazar testified that he was serving sentences for armed
    bank robbery and possession of contraband. He confirmed
    that he was a Sureño, and that the Mexican Mafia controls the
    Sureños “to an extent.” According to Salazar, the white
    inmates and the Sureños were “friendly” and “would hang out
    together.”
    On April 11, 2005, Salazar and Scopazzi started to drink
    wine together “right after breakfast . . . approximately 7 in the
    morning.” Scopazzi became “overly drunk. He was loud.
    He was being physical with people . . . hitting on people. . . .”
    Salazar had never before observed Scopazzi in this condition.
    Murillo told Salazar that Scopazzi “had disrespected
    [Murillo] in a sense where he was using the restroom on the
    toilet and [Scopazzi] opened the door and said something to
    the effect of, I could’ve got you, something like that.”
    UNITED STATES V. RODRIGUEZ                    15
    Although Murillo and Scopazzi were friends, Murillo was
    “upset about what happened.” Salazar went to Scopazzi’s cell
    to talk to him. Salazar intended to tell Scopazzi that Scopazzi
    “was drunk, and that he was disrespecting people and he
    needed to go to sleep.” Salazar asked Scopazzi “what’s up
    with you and [Murillo]?” According to Salazar, Scopazzi
    jokingly said that he and Murillo could go to the television
    room and fight. Scopazzi eventually apologized. Salazar did
    not observe any shanks or other weapons in Scopazzi’s cell.
    After speaking with Scopazzi, Salazar informed Murillo
    that Scopazzi had apologized, and suggested that Murillo talk
    to Scopazzi the next day when Scopazzi was no longer
    intoxicated. However, Murillo “was upset over the
    disrespect and he felt that he had that apology coming from
    [Scopazzi] . . .” According to Salazar, he did not know that
    Scopazzi was going to be harmed and did not realize that
    Scopazzi had been stabbed until after the incident. Although
    he described himself as a mediator, Salazar acknowledged
    that he did not accompany Murillo to Scopazzi’s cell.
    After the assault on Scopazzi, Salazar observed a shank
    in Rodriguez’s cell. Rodriguez did not tell Salazar that
    Scopazzi had attacked them. Salazar learned that Scopazzi
    had been stabbed from “the white guys on the tier.”
    Murillo testified that, while he was using the toilet in his
    cell, Scopazzi entered Murillo’s cell and “put his hands on his
    waist” and said, “I could have got you slipping . . .” Murillo
    thought that Scopazzi “was playing around.” Later in the
    day, Scopazzi entered Murillo’s cell with Ultsch and
    Scopazzi “mov[ed] his body back and forth like he wanted to
    punch [Murillo] . . .” Murillo did not believe that “they were
    playing around anymore.”
    16             UNITED STATES V. RODRIGUEZ
    Murillo talked to Salazar because he “didn’t want this to
    escalate into a bigger problem.” Murillo told Salazar that
    “[t]hese guys keep coming to my cell and disrespecting
    me. . . .” Although Salazar told Murillo that Scopazzi had
    apologized, Murillo went to Scopazzi’s cell for a direct
    apology. Murillo denied having a shank when he went to
    Scopazzi’s cell. According to Murillo, Scopazzi started
    swearing at Murillo and reached for a shank. According to
    Murillo, he disarmed Scopazzi and used Scopazzi’s shank to
    stab Scopazzi in self-defense.
    Rodriguez testified that, when Rodriguez, Murillo, and
    Mujica went to Scopazzi’s cell, they did not have any shanks.
    Scopazzi started to scream at them when they entered the cell
    and Rodriguez thought that Rondeau had a shank, although he
    never saw it. According to Rodriguez, he saw a shank tucked
    into Scopazzi’s waistband.
    James Reed Harris (Harris), an inmate at the Victorville
    federal prison who was serving sentences for bank robbery
    and “weapons, assault,” testified that he was Davis’ cellmate
    on the day of the assault.               Davis had injected
    methamphetamine at least twice, had not slept for four days,
    and was “getting real paranoid.” Harris described Davis as
    “acting rational enough,” but Harris was concerned that Davis
    “might fall over . . .” Harris explained that he was “testifying
    because Ryan Davis [was] lying to get a time cut.”
    The jury convicted Murillo and Rodriguez of conspiracy
    to commit murder, first degree murder, and assault with a
    dangerous weapon with intent to do bodily harm as to Ultsch
    and Rondeau. The jury acquitted Murillo and Rodriguez of
    assault with intent to commit murder as to Ultsch and
    Rondeau.
    UNITED STATES V. RODRIGUEZ                     17
    The jury convicted Mujica of conspiracy to commit
    murder and first degree murder, but acquitted Mujica of
    assault with intent to commit murder and assault with a
    dangerous weapon with intent to do bodily harm as to Ultsch
    and Rondeau.
    Appellants filed a motion for new trial because the
    government failed to disclose that Davis had received an
    undisclosed sentence reduction and had served as a DEA
    informant.5 Appellants maintained that Davis had a tacit
    agreement with the government for a sentence reduction
    because the government sought to reduce Davis’ sentence on
    the same day as the verdicts were rendered. The motion was
    denied.
    Appellants filed timely notices of appeal.
    II. STANDARDS OF REVIEW
    “We review de novo whether an evidentiary error rises to
    the level of a constitutional violation. . . .” United States v.
    Pineda-Doval, 
    614 F.3d 1019
    , 1032 (9th Cir. 2010) (citation
    omitted).
    “We review the district court’s evidentiary rulings for
    abuse of discretion and its underlying factual determinations
    for clear error.” United States v. Lukashov, 
    694 F.3d 1107
    ,
    1114 (9th Cir. 2012) (citation omitted).
    “We review de novo a district court’s denial of a new trial
    motion based on a Brady violation.” United States v.
    5
    We granted a limited remand for the district court to consider
    Appellants’ motion.
    18              UNITED STATES V. RODRIGUEZ
    Sedaghaty, 
    728 F.3d 885
    , 899 (9th Cir. 2013) (citation
    omitted). “Likewise, the question of materiality is a legal
    matter that we review de novo.” 
    Id. (citations, alteration,
    and
    internal quotation marks omitted).
    We also review de novo the district court’s denial of a
    new trial based on an asserted Mooney-Napue violation. See
    United States v. Houston, 
    648 F.3d 806
    , 814 (9th Cir. 2011).
    III.      DISCUSSION
    A. Medical Evidence Concerning Scopazzi’s Death
    Appellants contend that the district court denied them a
    complete defense by improperly excluding evidence that
    gross medical negligence and Scopazzi’s removal of his
    breathing tube contributed to Scopazzi’s death. Appellants
    maintain that the excluded medical evidence was relevant to
    Appellants’ defense that the stab wounds were not the
    proximate cause of Scopazzi’s death and that they lacked the
    requisite intent to kill Scopazzi.
    The resolution of Appellants’ evidentiary challenge is
    largely controlled by our decision in Pineda-Doval. In that
    case, Pineda-Doval challenged his convictions for “ten counts
    of transportation of illegal aliens resulting in death.” Pineda-
    
    Doval, 614 F.3d at 1022
    . He maintained that “the jury should
    have been instructed that it could find the defendant guilty
    only if his conduct was the proximate cause of the ten
    charged deaths. . . .” 
    Id. Pineda-Doval argued
    that the
    proximate cause of the aliens’ death was the negligent
    deployment by Border Patrol agents of a spike strip that
    caused the defendant’s vehicle to flip over. See 
    id. at 1024.
    Prior to trial, the district court granted the government’s
    UNITED STATES V. RODRIGUEZ                    19
    motion in limine to exclude as irrelevant evidence that the
    Border Patrol agents had failed to comply with the requisite
    procedures for deployment of the spike strip. See 
    id. Pineda-Doval argued
    that the district court failed to
    properly instruct the jury that the “resulting in death” element
    required proof that his acts were the proximate cause of the
    aliens’ deaths. 
    Id. at 1025.
    We observed that “[a] basic tenet
    of criminal law is that, when a criminal statute requires that
    the defendant’s conduct has resulted in an injury, the
    government must prove that the defendant’s conduct was the
    legal or proximate cause of the resulting injury. . . .” 
    Id. at 1026
    (citation and internal quotation marks omitted). We
    explained that proof of proximate cause required a showing
    by the government that the harm suffered by the victim was
    a foreseeable outcome of the defendant’s conduct. See 
    id. at 1028.
    The proximate cause showing is more easily met when
    the intervening event is “not a coincidence or unrelated to the
    defendant’s prior conduct, but rather was a response to that
    conduct.” 
    Id. When the
    intervening event is a response to the
    defendant’s conduct, “the question is whether the intervening
    act was abnormal—that is, whether, looking at the matter
    with hindsight, it seems extraordinary. . . .” 
    Id. (citation omitted).
    We held:
    Pineda-Doval’s failed attempt to swerve
    around the spike strip was the proximate
    cause of the deaths of ten individuals. It was
    entirely foreseeable that the Border Patrol
    would deploy a [spike strip] against the
    defendant’s Suburban and that Pineda-Doval’s
    dangerous driving would end in an
    accident. . . . No reasonable jury could have
    20             UNITED STATES V. RODRIGUEZ
    found that a car accident was an extraordinary
    result.
    
    Id. at 1029.
    We rejected the defendant’s argument that the Border
    Patrol agents’ negligence “constituted a superseding cause of
    the accident. . . .” 
    Id. at 1029.
    We opined:
    If we assume that [the Border Patrol agent]
    made a mistake by pulling the [spike strip]
    across the road several seconds too early, this
    mistake was not so extraordinary as to break
    the chain of causation. Pineda-Doval created
    the dangerous conditions . . . and, because he
    refused to pull over in response to [the Border
    Patrol agent’s] lights and sirens, forced the
    Border Patrol to use drastic measures to
    stop him. The resulting deaths of his
    ten passengers were tragic, but not
    unexpected. . . .
    
    Id. at 1029–30.
    We held that any error in the district court’s exclusion of
    evidence that the Border Patrol agents were negligent in
    failing to follow the requisite procedures for deployment of
    the spike strip was harmless. “[O]ccasional negligence that
    should have been anticipated by the defendant does not defeat
    proximate cause. . . .” 
    Id. at 1029
    (citation and internal
    quotation marks omitted). “To show that the actions of [the
    Border Patrol agent] constituted a superseding cause that
    broke the chain of causation between Pineda-Doval’s
    dangerous driving, that negligence would have had to be so
    UNITED STATES V. RODRIGUEZ                   21
    extraordinary that it would be unfair to hold the defendant
    responsible for the resulting accident and deaths.” 
    Id. at 1034
    (citation and internal quotation marks omitted). “Even
    assuming that the defendant persuaded the jury that timing
    was essential to the correct and safe deployment of [the spike
    strip] and that [the Border Patrol agent] made the mistake of
    pulling the spike strip across the road several seconds too
    early, no reasonable jury could have found that [the Border
    Patrol agent’s] actions were extraordinary and could not have
    been foreseen by [the defendant].” 
    Id. (citations and
    footnote
    reference omitted). Therefore,“[t]he district court’s error in
    excluding evidence of [the Border Patrol] policies on spike
    strips was harmless beyond a reasonable doubt.” 
    Id. Similarly, in
    this case we conclude that any error in the
    district court’s exclusion of evidence concerning medical
    negligence or Scopazzi’s removal of his breathing tube was
    harmless beyond a reasonable doubt. Because medical
    treatment was a foreseeable response to Appellants’ conduct
    of stabbing Scopazzi, proximate cause was established by the
    government. See 
    id. at 1028.
    Appellants failed to proffer
    evidence establishing medical negligence as a superseding
    cause of Scopazzi’s death. To make the required showing,
    Appellants would have to demonstrate that medical
    negligence and Scopazzi’s removal of his breathing tube were
    “so extraordinary that it would be unfair to hold [Appellants]
    responsible for the resulting . . . death[ ].” 
    Pineda-Doval, 614 F.3d at 1034
    (citation and internal quotation marks
    omitted); see also Mitchell v. Prunty, 
    107 F.3d 1337
    , 1341
    n.8 (9th Cir. 1997), as amended, overruled on other grounds
    by Santamaria v. Horsley, 
    133 F.3d 1242
    , 1248 (9th Cir.
    1998) (observing that “if gross maltreatment of the wound
    was the sole cause of death, the person inflicting the wound
    will not be liable, because the wound was not the proximate
    22             UNITED STATES V. RODRIGUEZ
    cause of death. In this case, gross maltreatment would have
    been required to render [the victim’s] gunshot wounds fatal.”)
    (citation and internal quotation marks omitted).
    As it was foreseeable in Pineda-Doval, that Border Patrol
    agents would deploy a spike strip to stop a fleeing suspect, it
    was similarly foreseeable in this case that a victim of multiple
    deep stab wounds would receive medical care. See Pineda-
    
    Doval, 614 F.3d at 1034
    . And, as we held in Pineda-Doval,
    any negligence in the foreseeable response to the stab wounds
    does not break the causation chain. See 
    id. The same
    is true
    regarding Scopazzi’s removal of his breathing tube. See
    Sedation and Delirium in the Intensive Care Unit, 14 New
    England J. of Med. 444 (Jan. 30, 2014) (discussing the
    accidental removal of endotracheal tube due to delirium and
    agitation); see also Peter Pressman, M.D., Delirium: An Acute
    Confusional State, April 23, 2014 (observing that “[a]cute
    confusional state, also known as delirium or encephalopathy,
    is so common in hospitals that it’s almost seen as routine by
    many hospital staff. Between 14 to 56% of all hospitalized
    patients develop confusion. Intubated patients in the
    intensive care unit have an even higher rate, reaching about
    82%. . . . Such agitated patients may also try to remove tubes
    or IV lines that are providing life-saving medications.”)
    (available at      http://neurology.about.com/od/Delirium/a/
    Delirium.htm)(last visited May 8, 2014).
    Dr. Morgan’s proffered testimony did not address whether
    medical negligence was the sole cause of Scopazzi’s death or
    even an intervening cause. Although Dr. Morgan purportedly
    opined that “the medical attention [Scopazzi] did receive fell
    well below well-recognized standards of care resulting in
    [Scopazzi’s] death,” Dr. Morgan did not state that
    extraordinary medical negligence or Scopazzi’s removal of
    UNITED STATES V. RODRIGUEZ                   23
    his breathing tube caused Scopazzi’s death independent of the
    stab wounds themselves. Although the district court ruled
    that Dr. Morgan could testify “regarding the nature of
    [Scopazzi’s] wounds and the degree of force used to cause
    them,” Dr. Morgan never actually testified. Appellants also
    informed the district court that they did not intend to rely on
    medical negligence as an affirmative defense. Thus, the
    district court’s exclusion of Appellants’ proffered evidence
    had no bearing on the fairness of Appellants’ trial because
    that evidence did not establish medical negligence or removal
    of the breathing tube as a superseding cause of Scopazzi’s
    death.
    Our conclusion that Appellants failed to proffer
    admissible evidence that extraordinary medical negligence or
    Scopazzi’s removal of his breathing tube constituted a
    supervening cause of Scopazzi’s death is bolstered by the
    Seventh Circuit’s rationale in Brackett v. Peters, 
    11 F.3d 78
    (7th Cir. 1993). In Brackett, the habeas petitioner was
    convicted of felony murder based on his rape and assault of
    an 85-year-old woman. See 
    id. at 79.
    The victim “was
    admitted to the hospital with a broken arm, a broken rib, and
    extensive bruises. During her stay in the hospital, which
    lasted several weeks, she—described as feisty before the rape
    and beating—became depressed, resisted efforts to feed her,
    and became progressively weaker.” 
    Id. (internal quotation
    marks omitted). After her transfer to a nursing home, she
    continued to regress, even though her physical injuries were
    healing. Because of her lack of appetite, her doctor ordered
    placement of a nasal gastric feeding tube. However, the tube
    could not be inserted, in part because the victim’s facial
    injuries made insertion of the tube too painful. See 
    id. Approximately ten
    days after her admission, the victim died
    when a large quantity of food became lodged in her trachea,
    24             UNITED STATES V. RODRIGUEZ
    asphyxiating her. See 
    id. The habeas
    petitioner contended
    that the negligence of the nurse who was feeding the victim
    caused her death. See 
    id. at 80.
    In rejecting the habeas petitioner’s argument and holding
    that the petitioner’s assault was the proximate cause of the
    victim’s death, the Seventh Circuit observed that “an act is a
    cause of an event if two conditions are satisfied: the event
    would not have occurred without the act; the act made the
    event more likely.” 
    Id. at 79.
    The Seventh Circuit opined
    that the nurse’s purported negligence was nothing more than
    another cause of the victim’s death. See 
    id. at 80.
    The
    Seventh Circuit concluded that “a murderer does not avoid
    conviction by pointing out that his act was only one of many
    causes that concurred to bring about his victim’s death.” 
    Id. “It is
    enough if his act was one of the causes-enough
    therefore if [the petitioner’s] assault made [the victim’s]
    death more likely and if, but for the assault, she would not
    have died as soon as she did. . . .” 
    Id. (citations omitted).
    “Death was the last link in a continuous series of events that
    began with the assault. [The victim] died a month later, never
    having returned home. . . .” 
    Id. The court
    emphasized that
    had the victim never been assaulted, it is unlikely that she
    would have been admitted to the hospital to die one month
    later. See 
    id. The petitioner
    also argued that the assault caused the
    victim to become clinically depressed and suicide-prone.
    According to the petitioner, the victim committed suicide by
    refusing to eat, and that suicide was a superseding cause of
    the victim’s death. See 
    id. at 80–81.
    The Seventh Circuit
    rejected this argument, reasoning that “[t]he fact that a
    psychiatric condition, whether or not by precipitating suicide,
    is one of the causes of a victim’s death does not excuse his
    UNITED STATES V. RODRIGUEZ                    25
    murderer. Otherwise, it would be open season on sufferers
    from mental illness.” 
    Id. at 81
    (citations omitted). The court
    contrasted a chance occurrence, such as a fire at a nursing
    home, that would be a superseding cause if death resulted.
    See 
    id. at 80.
    Other circuits have also held that defendants are liable for
    murder notwithstanding additional occurrences. For example,
    in United States v. Swallow, 
    109 F.3d 656
    (10th Cir. 1997),
    the Tenth Circuit affirmed the defendant’s murder
    convictions despite the defendant’s argument that the district
    court erred in failing to provide a “proposed instruction
    characteriz[ing] an independent intervening cause as the
    unforeseeable gross negligence of a third party that relieves
    the defendant of responsibility for the death of the
    victim. . . .” 
    Id. at 659
    (citations omitted). In rejecting the
    defendant’s argument that negligence on the part of rescuers
    contributed to the victims’ deaths, the Tenth Circuit held that
    “in cases involving death from injuries inflicted in an assault,
    courts have uniformly held that the person who inflicted the
    injury will be liable for the death despite the failure of third
    persons to save the victim.” 
    Id. at 660
    (citations and
    alteration omitted).
    Similarly, in United States v. Guillette, 
    547 F.2d 743
    (2d
    Cir. 1976), the Second Circuit held that the defendant was
    liable for the death of a victim who may have accidently
    triggered a bomb. See 
    id. at 747–48.
    “The trial judge
    instructed the jury that even if [the victim] died accidentally
    through his own actions, the defendants would nonetheless be
    guilty of conspiracy with death resulting if [the victim’s]
    death was induced or brought about by some act of a
    conspiracy in furtherance of the purposes of a conspiracy.”
    
    Id. at 748.
    The Second Circuit ruled that “[a] fundamental
    26             UNITED STATES V. RODRIGUEZ
    principle of criminal law is that a person is held responsible
    for all consequences proximately caused by his criminal
    conduct. The concept of proximate cause incorporates the
    notion that an accused may be charged with a criminal
    offense even though his acts were not the immediate cause of
    the victim’s death or injury.” 
    Id. at 749
    (citation omitted).
    “In many situations giving rise to criminal liability, the death
    or injury is not directly caused by the acts of the defendant
    but rather results from intervening forces or events, such as
    negligent medical treatment, escape attempts, or the negligent
    or intentional acts of a third party.” 
    Id. “Where such
    intervening events are foreseeable and naturally result from
    a perpetrator’s criminal conduct, the law considers the chain
    of legal causation unbroken and holds the perpetrator
    criminally responsible for the resulting harm.” 
    Id. (citations omitted);
    see also United States v. Rodriguez, 
    279 F.3d 947
    ,
    950–51 (11th Cir. 2002) (holding in the sentencing
    enhancement context that “one may be held criminally liable
    for a victim’s death even where medical negligence or
    mistreatment also contributed to the victim’s death”) (citation
    omitted).
    State courts have also consistently held that the defendant
    must demonstrate extraordinary medical negligence as the
    sole cause of death to break the causation chain. See, e.g.,
    People v. Mars, 
    985 N.E.2d 570
    , 575 (Ill. App. Ct. 2012), as
    modified (“The presumption [of causation] must be rebutted
    by the defendant’s presentation of contrary evidence that the
    sole cause of death was the intervening gross negligence of
    physicians. Unskilled or improper medical treatment that
    aggravates a victim’s preexisting condition or contributes to
    the victim’s death is considered reasonably foreseeable and
    does not constitute an intervening act unless the treatment is
    so bad that it can be classified as gross negligence or
    UNITED STATES V. RODRIGUEZ                     27
    intentional malpractice. . . .”) (citations omitted) (emphasis in
    the original); State v. Shabazz, 
    719 A.2d 440
    , 445 (Conn.
    1998) (“The rule . . . that such gross negligence may permit
    the defendant to escape liability when it was the sole cause of
    the death, strikes an appropriate balance between the notions
    of criminal responsibility for one’s conduct, on one hand, and
    intervening cause, on the other.”) (citation omitted); State v.
    Kirby, 
    39 P.3d 1
    , 12 (Kan. 2002) (“It is clear that the
    physicians’ actions were not so unusual, abnormal, or
    extraordinary that they could not have been foreseen. The
    physicians’ negligence, if any, did not supersede the effect of
    the wounds inflicted by [the defendant] so as to become the
    sole legal cause of [the victim’s] death.”); People v. Roberts,
    
    826 P.2d 274
    , 295 (Cal. 1992) (in bank), as modified (“If a
    person inflicts a dangerous wound on another, it is ordinarily
    no defense that inadequate medical treatment contributed to
    the victim’s death. To be sure, when medical treatment is
    grossly improper, it may discharge liability for homicide if
    the maltreatment is the sole cause of death and hence an
    unforeseeable intervening cause. . . .”) (citations omitted).
    Given the weight of such consistent federal and state
    precedent, we conclude that Appellants failed to proffer any
    evidence that extraordinary medical negligence or Scopazzi’s
    removal of his breathing tube was the sole cause of
    Scopazzi’s death. Indeed, Scopazzi would not have needed
    medical care or a breathing tube absent Appellants’ infliction
    of five stab wounds, including a wound that punctured
    Scopazzi’s lung. The alleged medical negligence or removal
    of Scopazzi’s breathing tube may have been “another cause
    of [Scopazzi’s] death,” but they were not supervening events
    exonerating Appellants from the death resulting from their
    assault. 
    Brackett, 11 F.3d at 80
    (citations omitted). It was
    not sufficient for Appellants to simply proffer some evidence
    28                UNITED STATES V. RODRIGUEZ
    of medical negligence or Scopazzi’s removal of his breathing
    tube without otherwise satisfying the standard for proximate
    cause. See 
    Pineda-Doval, 614 F.3d at 1034
    ; see also
    
    Guillette, 547 F.2d at 749
    (“Where such intervening events
    are foreseeable and naturally result from a perpetrator’s
    criminal conduct, the law considers the chain of legal
    causation unbroken and holds the perpetrator criminally
    responsible for the resulting harm. This principle applies even
    where the direct cause of death is a force set in motion by the
    victim himself. . . .”) (citations omitted).6
    United States v. Main, 
    113 F.3d 1046
    (9th Cir. 1997) does
    not compel a contrary result. In Main, we delineated the
    applicable standard for proximate cause involving an
    involuntary manslaughter conviction resulting from the
    defendant’s reckless driving while intoxicated. See 
    id. at 1047.
    In reversing the conviction, we held that the district
    court failed to properly instruct the jury that it must find that
    the defendant’s acts were the proximate cause of the victim’s
    death. See 
    id. at 1049–50.
    We observed that “[a]ll of the
    authorities agree that to be guilty of involuntary manslaughter
    6
    Consistent with its prior rulings on the government’s motions in limine,
    the district court did not abuse its discretion when it denied Appellants’
    request to cross-examine Dr. Holt, the medical examiner, regarding his
    description of “the sequelae of puncture wounds” ultimately leading to
    Scopazzi’s death. Appellants specifically sought to question Dr. Holt
    concerning Scopazzi’s removal of his breathing tube, a sudden loss of
    blood, cardiac arrest, and brain swelling. Dr. Holt’s testimony did not
    open the door to this additional medical evidence because Dr. Holt
    acknowledged that the complications “flowed from the fact that
    [Scopazzi] was stabbed.” In any event, Appellants’ proffer did not satisfy
    the proximate cause standard of complications “so extraordinary that it
    would be unfair to hold [Appellants] responsible for the resulting . . .
    death[ ].” 
    Pineda-Doval, 614 F.3d at 1034
    (citation and internal quotation
    marks omitted); see also 
    Brackett, 11 F.3d at 80
    .
    UNITED STATES V. RODRIGUEZ                           29
    the harmful result must be within the risk foreseeably created
    by the accused’s conduct; if the physical causation is too
    remote, the law will not take cognizance of it. . . .” 
    Id. at 1049.
    We considered the foreseeability determination more
    difficult when the manslaughter charges stem from excessive
    speed or drunk driving because many individuals speed
    and/or drive while impaired without killing anyone. See 
    id. Therefore, the
    foreseeability determination would require
    careful examination of the individual “conduct engaged in.”
    
    Id. We held
    that reversal of the conviction was warranted
    because “[w]hen the jury is not told that it must find that the
    victim’s death was within the risk created by the defendant’s
    conduct an element of the crime has been erroneously
    withdrawn from the jury.” 
    Id. at 1050
    (citations omitted).7
    In stark contrast to Main, Appellants’ convictions were
    not premised on the more ambiguous acts of “excessive speed
    or drunk driving.” 
    Main, 113 F.3d at 1049
    . Rather,
    Appellants’ use of deadly weapons to directly inflict serious
    stab wounds carried the completely foreseeable risk that
    Scopazzi’s injuries would result in death. Moreover, the
    district court included the concept of proximate cause in the
    7
    We offered the following example of a sufficient intervening cause:
    “Suppose [the victim] had been pinned in the wreck and then eaten by a
    bear. His death would have been the result of the wreck; but for [the
    defendant’s] driving, he would not have been killed, yet a jury could find
    as a fact that the death was not within the risk that [the defendant] had
    created. In the language of the American Law Institute death from a bear
    was not within the risk foreseeably created by the reckless driving[.]”
    
    Main, 113 F.3d at 1049
    (citation omitted).
    30                UNITED STATES V. RODRIGUEZ
    instruction on voluntary manslaughter, and the concept of
    foreseeability in other instructions.8
    Because Appellants failed to demonstrate that any
    medical negligence or removal of a breathing tube was “so
    extraordinary that it would be unfair to hold [Appellants]
    responsible for the resulting . . . death[ ],” 
    Pineda-Doval, 614 F.3d at 1034
    (citation and internal quotation marks
    omitted), and because the jury instructions included the
    concepts of foreseeability and proximate cause, the district
    court acted within its discretion when it cabined the medical
    evidence.
    B. Evidence of Gang Affiliation
    Appellants next contend that the district court erred in
    admitting irrelevant and prejudicial evidence concerning
    Appellants’ alleged connection to the Mexican Mafia.
    Appellants also maintain that the district court erred in
    holding that the evidence’s probative value outweighed any
    prejudice under Federal Rule of Evidence 403.
    8
    Appellants’ reliance on United States v. Chouteau, 
    102 U.S. 603
    (1880) is also misplaced. In Chouteau, the Supreme Court considered
    whether a distiller was liable for breach of certain bond conditions. See
    
    id. at 608.
    Within that context, the Supreme Court merely observed that
    “[i]f, for example, a party should charge another with inflicting upon his
    person a wound by which he lost an arm, it would be a good defence to
    show that the loss resulted from unskilful medical treatment or neglect and
    not from the wound inflicted. So here, it is enough for the sureties to
    show that the loss to the government was produced by other means than
    the particular breach of duty by their principal, of which the government
    complains. . . .” 
    Id. at 609.
    Needless to say, the law has evolved in the
    century-plus since Chouteau was decided. See 
    Pineda-Doval, 614 F.3d at 1034
    .
    UNITED STATES V. RODRIGUEZ                   31
    In United States v. Santiago, 
    46 F.3d 885
    (9th Cir. 1995),
    we rejected an analogous evidentiary challenge. In that case,
    to establish the motive for the defendant’s first degree murder
    of another inmate, the government introduced a cellmate’s
    testimony that the defendant sought to become a member of
    the Mexican Mafia. See 
    id. at 887–88.
    In affirming the
    district court’s admission of evidence concerning the
    defendant’s ties to the Mexican Mafia, we observed that the
    testimony did not violate Rule 404(b) because it “did not
    relate to other crimes,” and it fell within the exception for
    evidence regarding motive. 
    Id. at 888–89.
    “[T]he testimony
    relating to the Mexican Mafia was necessary to explain the
    reason that Santiago would kill a stranger – to be accepted
    into the gang – and to show how and why other inmates
    assisted him in obtaining the weapon.” 
    Id. at 889.
    We
    rejected the argument that the government’s use of the
    testimony was a pretense intended to denigrate the defendant
    for his affiliation with a prison gang. See 
    id. at 889–90.
    Because the evidence reflected that the defendant had
    expressed interest in the gang and had associated with gang
    members, including on the night before the murder, a
    sufficient foundation was laid to admit the testimony. See 
    id. at 890.
    We similarly conclude that testimony relating to the
    Mexican Mafia was relevant to Appellants’ murder of
    Scopazzi, and that its probative value was not substantially
    outweighed by any prejudice. Although Appellants attempt
    to distinguish Santiago on the basis that the government did
    not present any evidence that Appellants stabbed Scopazzi
    based on their ties to the Mexican Mafia, the record supports
    a contrary conclusion. As in Santiago, the Mexican Mafia
    testimony was critical to the government’s theory that
    Appellants did not act in self-defense and that their attack on
    32             UNITED STATES V. RODRIGUEZ
    Scopazzi for seemingly insignificant acts of disrespect was
    motivated by their ties to the Mexican Mafia. See 
    Santiago, 46 F.3d at 889
    –90. The government also introduced the kite
    from Murillo’s cell that implied the attack on Scopazzi was
    motivated by Scopazzi’s disrespect of the Sureños.
    Appellants’ trial was also permeated with references to
    their gang affiliations, and Agent Evanilla’s expert testimony
    addressed the connection between the Sureños and the
    Mexican Mafia within the prison gang hierarchy. Given
    Appellants’ admitted gang connections, the expert testimony
    concerning the Mexican Mafia and photographs of Appellants
    with members of the Mexican Mafia was not unduly
    prejudicial as “the Mexican Mafia was not the entire theme of
    the trial, so as to infect the trial with the threat of guilt by
    association. . . .” 
    Santiago, 46 F.3d at 889
    (citation,
    alteration, and internal quotation marks omitted). This is
    particularly true in this case where the trial focused primarily
    on the events that transpired in Scopazzi’s cell and the jury
    was presented with numerous photographs and videos of the
    events without reference to Appellants’ connections to the
    Mexican Mafia.
    Notably, the district court also took several steps to
    minimize any undue prejudice. In particular, the district court
    permitted only “a limited number of photographs of
    [Appellants] posing with certain members of the Mexican
    Mafia” and “brief testimony by qualified witnesses regarding
    the hierarchy, customs, practices and tenets of the Mexican
    Mafia and its relationship and connection to the Sureños.”
    The district court also committed to “include in its voir dire
    of prospective jurors examination on this subject and its
    effect, if any, on any juror’s ability to judge the case fairly
    and objectively.” Appellants rejected the district court’s offer
    UNITED STATES V. RODRIGUEZ                     33
    to provide a limiting instruction concerning why the Mexican
    Mafia testimony was being admitted into evidence. See
    United States v. Decoud, 
    456 F.3d 996
    , 1012 (9th Cir. 2006)
    (rejecting evidentiary challenge in part because the defendant
    “did not take up the district court on its offer to provide the
    jury with a limiting instruction that could have mitigated, if
    not negated, [the defendant’s] concerns”).
    We conclude that the district court did not abuse its
    discretion in admitting evidence pertaining to the connection
    between the Sureños and the Mexican Mafia as relevant to
    Appellants’ motive in attacking Scopazzi. See 
    Santiago, 46 F.3d at 889
    –90; see also United States v. Major, 
    676 F.3d 803
    , 810 (9th Cir. 2012) (holding that the district court did
    not abuse its discretion in admitting gang affiliation evidence
    as relevant to motive).
    Appellants’ reliance on Kennedy v. Lockyer, 
    379 F.3d 1041
    (9th Cir. 2004), as amended, Spivey v. Rocha, 
    194 F.3d 971
    (9th Cir. 1999), and Dawson v. Delaware, 
    503 U.S. 159
    (1992) is misplaced as those cases are entirely
    distinguishable. In Kennedy, we did not address an
    evidentiary challenge to gang affiliation evidence. Instead,
    we held that a habeas petitioner was prejudiced because the
    attorney for his retrial was not provided a complete trial
    transcript that included the trial court’s prior ruling excluding
    such evidence. See 
    Kennedy, 379 F.3d at 1042
    –43. Because
    the prosecution elicited the precluded testimony in the second
    trial in violation of the trial court’s prior order, we held that
    the petitioner was prejudiced in part because “where, as here,
    gang evidence is proffered to prove a substantive element of
    the crime (and not for impeachment purposes), it would likely
    be unduly prejudicial. . . .” 
    Id. at 1056
    (citation and internal
    quotation marks omitted).
    34             UNITED STATES V. RODRIGUEZ
    In Spivey, we considered whether the trial court erred in
    excluding evidence of the witnesses’ gang affiliation
    proffered by the defendant. See 
    Spivey, 194 F.3d at 977
    . The
    trial court excluded the evidence because it did not support
    the defendant’s assertion that the victim “was killed by a
    phantom killer” and there was already sufficient evidence of
    the witness’s potential bias. 
    Id. We held
    that, because the
    evidence was purely speculative, exclusion of the evidence
    did not render the defendant’s trial fundamentally unfair. See
    
    id. at 979.
    Contrary to Appellants’ assertion, Spivey did not
    hold that the prosecution was required to establish that gang
    affiliation was the actual motive for the murder. Instead, we
    articulated that, under California law, “[i]n order for evidence
    of another suspect to be admissible . . . there must be direct or
    circumstantial evidence linking the third person to the actual
    perpetration of the crime. Motive or opportunity is not
    enough. . . .” 
    Spivey, 194 F.3d at 978
    (citations and internal
    quotation marks omitted).
    In Dawson, the Supreme Court held that evidence
    concerning the Aryan Brotherhood was inadmissible because
    it contravened the defendant’s associational rights. See
    
    Dawson, 503 U.S. at 164
    –65. The Supreme Court opined that
    “the Aryan Brotherhood evidence was not tied in any way to
    the murder of [the defendant’s] victim” and that “the
    inference which the jury was invited to draw . . . tended to
    prove nothing more than the abstract beliefs of [a particular
    Aryan Brotherhood] chapter. . . .” 
    Id. at 166.
    Unlike in
    Dawson, the Mexican Mafia evidence in this case was “tied
    to the murder” of Scopazzi as evidence of motive.
    UNITED STATES V. RODRIGUEZ                   35
    C. Brady and Mooney-Napue Claims
    1. Non-Disclosure of A Tacit Agreement That
    Davis Would Receive A Sentence Reduction
    Appellants posit that a new trial is warranted because the
    government’s failure to disclose a tacit agreement to reduce
    Davis’ sentence contravened Brady. “Under Brady, the
    suppression by the prosecution of evidence favorable to an
    accused upon request violates due process where the evidence
    is material either to guilt or to punishment.” United States v.
    Stinson, 
    647 F.3d 1196
    , 1208 (9th Cir. 2011), as amended
    (citation and internal quotation marks omitted). “There are
    three components of a Brady violation: the evidence at issue
    must be favorable to the accused, either because it is
    exculpatory, or because it is impeaching; that evidence must
    have been suppressed by the State, either willfully or
    inadvertently; and prejudice must have ensued.” 
    Id. (citation, alteration,
    and internal quotation marks omitted). “To
    determine whether prejudice exists, we look to the materiality
    of the suppressed evidence. When looking to materiality, the
    question is whether admission of the suppressed evidence
    would have created a reasonable probability of a different
    result, so the defendant must show only that the government’s
    evidentiary suppression undermines confidence in the
    outcome of the trial.” 
    Id. (citation and
    internal quotation
    marks omitted).
    The record reflects that there was no Brady violation
    premised on Davis’ cooperation. Although the government
    initiated the process under Federal Rule of Criminal
    Procedure 35 to reduce Davis’ sentence on the same day the
    jury found Appellants guilty, we are unable to conclude that
    this temporal proximity alone establishes a Brady violation.
    36                UNITED STATES V. RODRIGUEZ
    At trial, Davis testified that early termination of his sentence
    was possible based on his cooperation. Davis related that the
    letter agreement required that he testify truthfully and that the
    agreement did not provide any promises of leniency or a
    sentence reduction contingent upon the trial’s outcome. As
    reflected by Davis’ testimony, the government fully disclosed
    the letter agreement and the FBI interviews.9 Appellants
    failed to demonstrate that any of the government’s post-
    verdict actions were inconsistent with the letter agreement or
    were premised on an undisclosed tacit agreement.10
    We conclude that no Brady violation occurred because
    there was no tacit agreement to disclose. See United States v.
    Price, 
    566 F.3d 900
    , 910 n.11 (9th Cir. 2009) (“If the record
    is conclusive that all relevant agents of the government did
    not know about the Brady material, then, of course, no Brady
    violation has occurred as the government has no obligation to
    produce information which it does not possess or of which it
    9
    Appellants maintain that Davis falsely denied that he expected any
    leniency based on his testimony. However, Appellants have not presented
    any evidence of a tacit agreement for leniency or that Davis was aware of
    any such agreement.
    10
    Appellants’ reliance on Sivak v. Hardison, 
    658 F.3d 898
    (9th Cir.
    2011) is misplaced. In that case, the witness testified that certain charges
    were dismissed but “he did not know whether the prosecutor’s office was
    involved in the dismissals.” 
    Sivak, 658 F.3d at 904
    . The witness also
    testified that he cooperated based on fears for his family’s safety and that
    he was not “seeking any particular favoritism from State authorities in
    exchange for his testimony . . .” 
    Id. at 903
    (internal quotation marks
    omitted). We held that there was a Brady violation based on undisclosed
    letters reflecting a tacit agreement for leniency. See 
    id. at 909–10.
    Davis,
    unlike the witness in Spivak, acknowledged that he hoped that his
    cooperation would result in a sentence reduction and no tacit agreement
    for leniency was unearthed.
    UNITED STATES V. RODRIGUEZ                             37
    is unaware. . . .”) (citation and internal quotation marks
    omitted) (emphasis in the original). The district court also
    cautioned the jury that Davis “may have received, or may
    receive, benefits from the government in connection with this
    case” and that the jury should examine Davis’ testimony
    “with greater caution than that of other witnesses.”11 Davis’
    credibility, therefore, was significantly undermined
    irrespective of any tacit agreement for a sentence reduction.
    2. Non-Disclosure of Davis As A DEA Informant
    Appellants argue that a new trial is required because the
    government failed to disclose that Davis served as a DEA
    informant.
    Although it is arguable that the government was required
    to disclose this information as impeachment evidence, see
    United States v. Si, 
    343 F.3d 1116
    , 1123 (9th Cir. 2003)
    (observing that “these [informant] reports can be considered
    favorable to [the defendant] because, as information about
    [the witness’s] ongoing informant activities, they would
    constitute impeachment evidence tending to show [the
    witness’s] motives in testifying for the government”), its
    disclosure would not “have led to a different result. . . .”
    United States v. Olsen, 
    704 F.3d 1172
    , 1184 (9th Cir. 2013)
    (citation omitted). As discussed, Davis’ credibility was
    sufficiently undermined by the defense given his admitted
    cooperation with the prosecution, his extensive criminal
    11
    Appellants maintain that the district court’s instruction was ineffective
    because it required the jury to speculate. However, it is unclear how the
    district court’s instruction was ineffective as it specifically cautioned the
    jury about the potential impact of any benefits Davis received for his
    cooperation.
    38             UNITED STATES V. RODRIGUEZ
    history, and his illicit prison activities. Although the DEA
    report may have further demonstrated Davis’ willingness to
    cooperate with the government, Appellants do not point to
    any benefits that Davis received from his cooperation,
    particularly as Appellants do not rebut the government’s
    representation that Davis was never classified as a DEA
    informant. “The cross-examination of [Davis] raised
    reasonable doubts as to his motivation for testifying and there
    was sufficient impeachment evidence for the jury to question
    seriously the veracity of [Davis’] original statement. Thus,
    regardless of the failure to disclose the informant status of
    [Davis], [Appellants] received a trial resulting in a verdict
    worthy of confidence.” Gentry v. Sinclair, 
    705 F.3d 884
    , 905
    (9th Cir. 2013), as amended (citation and internal quotation
    marks omitted); see also 
    Si, 343 F.3d at 1123
    (holding that
    information of witness’s role as an informant in unrelated
    cases was not material).
    3. Mooney-Napue Violation
    Appellants contend that the government knowingly failed
    to correct Davis’ false testimony that he was not promised a
    sentence reduction in violation of Mooney and Napue.
    “A conviction obtained using knowingly perjured
    testimony violates due process, even if the witness’s perjured
    testimony goes only to his credibility as a witness and not to
    the defendant’s guilt.” United States v. Houston, 
    648 F.3d 806
    , 814 (9th Cir. 2011) (citations omitted). “The
    government’s failure to correct testimony that it later learns
    is perjured is also a Mooney–Napue violation.” 
    Id. (citation omitted).
    “To prevail on a Mooney–Napue claim, the
    defendant must show that (1) the testimony was actually
    false, (2) the prosecution knew or should have known that the
    UNITED STATES V. RODRIGUEZ                           39
    testimony was actually false, and (3) that the false testimony
    was material.” 
    Id. (citation, alteration,
    and internal quotation
    marks omitted). “In assessing materiality under Napue, we
    determine whether there is any reasonable likelihood that the
    false testimony could have affected the judgment of the jury;
    if so, then the conviction must be set aside. Under this
    materiality standard, the question is not whether the
    defendant would more likely than not have received a
    different verdict with the evidence, but whether in its absence
    he received a fair trial, understood as a trial resulting in a
    verdict worthy of confidence.” 
    Id. (citation omitted).
    “However, if it is established that the government knowingly
    permitted the introduction of false testimony reversal is
    virtually automatic.” 
    Id. (citation omitted).
    Appellants’ Mooney-Napue claim is premised on their
    contention that there was a tacit agreement that the
    government would assist Davis in receiving a sentence
    reduction based on his favorable testimony. However,
    Appellants failed to proffer any evidence of a tacit agreement,
    particularly as the government’s post-verdict actions were
    consistent with the fully disclosed letter agreement and with
    Davis’ testimony that the letter agreement was not contingent
    upon the trial’s outcome. Appellants are unable to
    demonstrate that Davis’ testimony “was actually false” or that
    “the prosecution knew or should have known that the
    testimony was actually false . . .” 
    Id. (citation omitted).
    Thus,
    a new trial was not warranted.12
    12
    Although Appellants maintain that cumulative error warrants a new
    trial, there were no errors, cumulative or otherwise, requiring reversal of
    Appellants’ convictions. See 
    Pineda-Doval, 614 F.3d at 1036
    (holding
    that even if the defendant had been permitted to introduce evidence
    concerning proximate cause, “[t]here was no prejudice, cumulative or
    40               UNITED STATES V. RODRIGUEZ
    IV.      CONCLUSION
    The district court’s exclusion of evidence concerning
    medical negligence and Scopazzi’s removal of his breathing
    tube does not warrant reversal of Appellants’ convictions.
    Appellants failed to demonstrate that any medical negligence
    related to Scopazzi’s multiple stab wounds and his removal
    of his breathing tube were the sole causes of Scopazzi’s death
    or were so extraordinary and unforeseeable as to absolve
    Appellants of liability for their vicious assault. The district
    court did not abuse its discretion in admitting evidence of
    Appellants’ connections to the Mexican Mafia to demonstrate
    Appellants’ motive for murdering Scopazzi.                Expert
    testimony concerning the connections between the Sureños
    and the Mexican Mafia within the prison gang hierarchy and
    photographs of Appellants with Mexican Mafia members did
    not render their trial unfair because the district court properly
    minimized any prejudice stemming from the evidence and
    Appellants’ trial was replete with admissible evidence
    regarding Appellants’ gang affiliations. Appellants also
    failed to demonstrate that a new trial was warranted based on
    the government’s failure to disclose immaterial information
    regarding Davis’ sentence reduction and his cooperation in a
    DEA investigation.
    AFFIRMED.
    otherwise”); see also United States v. Jeremiah, 
    493 F.3d 1042
    , 1047 (9th
    Cir. 2007), as amended (“[B]ecause we hold that there was no error
    committed by the district court, [Appellants’] theory of cumulative error
    necessarily fails.”).