Full opinion text
OPINION IKUTA, Circuit Judge: Anthony Gadson and Willie Wilson appeal their convictions for conspiracy to distribute more than 500 grams of cocaine, possession with intent to distribute controlled substances, and possession of firearms in furtherance of their conspiracy and possession of controlled substances. Wilson also appeals his conviction for retaliation against a witness. On appeal, they challenge various evidentiary rulings, the correctness of certain jury instructions, the sufficiency of the evidence as to two counts, and sentencing determinations. We affirm the convictions. I During the period from March 2009 through February 2010, a residence at 5260 Fouts Avenue in Fairbanks, Alaska, was the hub of a drug trafficking operation. Two brothers, Brandon and Joshua Haynes, along with Donte Edwards, lived at the Fouts house. Gadson, a brother of Brandon and Joshua Haynes, visited the house from time to time, though he lived in Anchorage. Wilson, a cousin of the Haynes brothers and Gadson, joined the group in November 2009. Joe Powell was also involved with the group and would sometimes complete transactions on behalf of Brandon Haynes. According to testimony at trial, Joshua Haynes regularly sold crack cocaine at or near the Fouts house. Joshua made ten sales of cocaine to Joshua Voaklander during the spring and summer of 2009, half of which were witnessed by Gadson. During one of the transactions at which Gadson was present, Joshua displayed an assault rifle hidden under his couch cushions to Voaklander, which Joshua said was “for when somebody comes in through the front door.” One of the sources for the cocaine was a person with the code name “Transporter” who brought drugs up from Anchorage to the Fouts house in Fairbanks. On the two occasions that Gadson’s trips to the Fouts house coincided with Transporter’s trips, Gadson picked up bags containing $40,000 to $50,000 in cash from Brandon Haynes. At one point, Transporter was- arrested for driving without a license, and Gadson complained that his arrest could have “messed everything up,” meaning “everybody go to jail.” Officer Avery Thompson, a member of the Alaska Statewide Drug Enforcement Unit, began investigating this drug conspiracy in early 2010. By February 2010, he suspected that the Fouts house was at the center of a drug operation. A confidential informant working with the investigation executed two controlled buys of cot caine from Edwards, one of which took place in the driveway of the Fouts house. Following the buy, Officer Thompson and other members of the Fairbanks police department obtained a search warrant for the Fouts house. Although no one was in the house at the time of the search, they saw footprints in the new snow leading away from the open kitchen window. Subsequent investigation revealed that these footprints belonged to Wilson, and that when the police arrived, Wilson escaped out the window in his bare feet and scrambled over to a friend’s house. Inside, Officer Thompson and the other police investigators found a shoe box on top of the living room couch containing approximately a kilogram of cocaine, another shoe box containing another kilogram of cocaine and some $29,000 in cash behind the drugs. Gadson’s fingerprints were identified on the second living room shoe box. A loaded shotgun and ballistic vests were found near the shoe boxes. Powder cocaine, crack cocaine, ecstasy, marijuana, drug paraphernalia, and more cash and money orders were found in various locations in the kitchen and dining room. The bedrooms contained more drugs. In one bedroom, the police found Wilson’s possessions, including prescription pill bottles in Wilson’s name and a ring with Wilson’s initials. Inside that room, the officers found powder cocaine, crack, marijuana, heroin, 156 tabs of ecstasy, and approximately $13,000 in cash. A loaded handgun was nearby on the floor. While the police were searching the Fouts house, Wilson had reached his friend’s house, and informed Edwards (who was also at the friend’s house) about the raid. Edwards and Wilson'drove to Gadson’s house in Anchorage and decided to stay there until things cooled off in Fairbanks. Brandon Haynes was also in Anchorage at the time. After about two weeks, Edwards returned to Fairbanks, and began buying drugs from Gadson for sale. But when Brandon Haynes returned to Fairbanks at the end of May, and resumed drug activities in a new location, Edwards switched back to Haynes as a supplier. At some point in November 2010, the police used a confidential informant named Donny Pitka to make a controlled buy from Brandon Haynes. Pitka asked Brandon to deliver the drugs to undercover police in a vehicle near Brandon’s new apartment on Adams Drive. Brandon had Powell deliver the cocaine, and the police arrested Powell when he approached the vehicle. The police then closed in on the Adams Drive apartment, arrested Brandon, and discovered cocaine, marijuana, ecstasy, oxycontin, and $14,000 in cash inside the apartment. With Brandon Haynes in police custody, Edwards began buying again from Gadson. In January 2011, Gadson sold Edwards seven or more ounces of, cocaine. By March 2011, Gadson moved up from Anchorage to 2805 Gillam Way in Fairbanks. On April 20, a federal grand jury indicted Gadson, Wilson, Brandon Haynes, Edwards, Powell, and others. Arrest warrants were issued for the defendants. Officer Thompson picked up Gadson’s trail at the end of April. After conducting several days of surveillance at Gadson’s Gillam Way house and observing a good deal of “short-term traffic” indicative of drug dealing, he obtained a search warrant for the residence and garage. Officers executed the warrant at the beginning of May and found a ballistic vest and around $3,950 cash in the house. They discovered another $38,430 in a bag in the unlocked garage. The officers did not recover any firearms or an appreciable amount of cocaine from the Gillam Way house. Later that day, Gadson was arrested in his vehicle with another $1,300 on his person. Wilson turned himself in a few days later after learning of the outstanding warrant. Further investigation of the items obtained from the Gillam Way house suggested they had been used in drug transactions. A drug dog named Marley gave positive alerts for the presence of narcotics when presented with cash found at Gadson’s house and on his person. Following their arrests, Gadson, Edwards, Wilson, and Powell were all detained in the same wing of the Fairbanks Correctional Center. Pitka, who had been involved in the controlled buy that led to Brandon Haynes’s arrest, was in the same prison on unrelated charges. After Powell learned about Pitka’s role from his attorney, word spread to the other co-eonspira-tors. In a series of recorded phone calls between Wilson and his cousin, Gabriella Haynes, Wilson discussed the police reports mentioning Pitka and told Gabriella Haynes that “the Cl’s here,” using the standard abbreviation for a confidential informant. A few days later, Wilson told Gabriella that “[s]nitches can’t go into the hallways.” On May 21, soon after the call to Gabriella Haynes, Wilson assaulted Pit-ka as he was walking down the hallway. The assault lasted two minutes and was captured on video. Although the details of the fight are disputed, the video recording shows Wilson punching Pitka, who suffered a number of abrasions, scratches, and bites from the encounter. The day after the assault, Wilson called Gabriella Haynes again and told her that he hit “Donny,” who had “started this shit,” and referenced the earlier controlled buy between Pitka and Brandon Haynes. On June 23, 2011, the government charged Gadson, Wilson, and others with five crimes: conspiracy to distribute, and possession with intent to distribute, more than 500 grams of cocaine and other controlled substances, in violation of 21 U.S.C. §§ 846, 841(a)(1), (b)(1)(B), (b)(1)(C), (b)(1)(D) (Count 1); possession with intent to distribute controlled substances, in violation of 21 U.S.C. § 841(a)(1), (b)(1)(B), (b)(1)(C), (b)(1)(D) (Count 2); possession of firearms in furtherance of Counts 1 and 2, in violation of 18 U.S.C. § 924(c)(1)(A)© (Count 3); and conspiracy to retaliate against a witness, in violation of 18 U.S.C. § 1513(e) (Count 5). The government also charged Wilson with attempting to kill a witness, in violation of 18 U.S.C. § 1513(a)(1)(B), (a)(2)(B) (Count 6), and retaliation against a witness, in violation of 18 U.S.C. § 1513(b)(2) (Count 7). On October 11, 2011, a jury found Gad-son and Wilson guilty of conspiracy to distribute, possession of drugs with intent to distribute, and possession of three firearms in furtherance of the conspiracy (Counts 1, 2 and 3). Wilson was also found guilty of retaliation against a witness (Count 7). Neither was found guilty of conspiring to retaliate against a witness (Count 5), and Wilson was acquitted of attempting to kill a witness (Count 6). On December 29, 2011, Gadson received a below-Guidelines sentence of 300 months of imprisonment and eight years of supervised release. The court attributed 10,-521,103 grams of drugs to Gadson on the basis of his involvement in the conspiracy, and the sentence included, among other things, a three-level enhancement for having a managerial role. On January 27, 2012, the court sentenced Wilson to 168 months of imprisonment and five years of supervised release, a sentence that also fell below the Guideline range. The court declined to give Wilson a minor role adjustment, noting that he had been entrusted to guard the drugs and cash in the Fouts house, and that he had sold drugs to Pitka and later assaulted him. On appeal, Gadson and Wilson challenge certain of the district court’s evidentiary rulings and jury instructions. They also contest the sufficiency of the evidence as to two counts. Finally, they challenge the district court’s sentencing determinations. We consider each of these challenges in turn. II We begin by addressing Gadson and Wilson’s challenges to the district court’s evidentiary rulings. Where those challenges have been preserved, we review the district court’s rulings for an abuse of discretion, and uphold them unless they are “illogical, implausible, or without support in inferences that may be drawn from the facts in the record.” United States v. Hinkson, 585 F.3d 1247, 1263 (9th Cir.2009) (en banc). We review de novo the district court’s interpretations of the legal standard for its decision. United States v. Waters, 627 F.3d 345, 351-52 (9th Cir.2010). A First, we consider Gadson’s argument that the district court abused its discretion by not admitting certain out-of-court statements by his brother, Brandon Haynes. In preparing for trial, Gadson learned that Brandon had made two statements to the police that were helpful to Gadson. Specifically, Brandon said that it was he who had put the $38,000 in cash into Gad-son’s garage at the Gillam Way house. Brandon also denied that he had given Gadson bags of $40,000 to $50,000, which contradicted Edwards’s testimony that he had witnessed those transactions. In addition, Brandon told Wilson in a jail conversation that “[y]ou and I both know [Gad-son] should not be in it,” possibly referring to the case arising out of the drug operation at the Fouts house. Gadson subpoenaed Brandon to testify at his trial, but Brandon invoked his Fifth Amendment right not to testify. At trial, Gadson moved to admit Brandon’s statements under Rule 804(b)(3) of the Federal Rules of Evidence. The district court denied the motion, ruling that Brandon had given inconsistent testimony, and that this evidence was “so suspect” that “it would be a miscarriage of justice to permit it.” Gadson argues that the district court erroneously interpreted the hearsay rules and that the district court thereby abused its discretion in disallowing the evidence. According to Gadson, although Brandon’s statements were hearsay, they were admissible as statements against interest under Rule 804(b)(3) of the Federal Rules of Evidence. Even if those statements did not qualify as statements against interest, Gadson contends that their exclusion robbed him of his- constitutional right to present a complete defense. Rule 804(b)(3) provides that out-of-court statements are not excluded by the rule against hearsay if the declarant is unavailable as a witness, and the statement (1) is “truly self-inculpatory,” meaning it was “sufficiently against the declarant’s penal interest that a reasonable person in the declarant’s position would not have made the statement unless believing it to be true,” Williamson v. United States, 512 U.S. 594, 603-04, 114 S.Ct. 2431, 129 L.Ed.2d 476 (1994) (internal quotation marks omitted), and (2) “is supported by corroborating circumstances that clearly indicate its trustworthiness,” Fed.R.Evid. 804(b)(3)(B). The district court did not misinterpret the hearsay rules and did not abuse its discretion in declining to admit Brandon’s statements under Rule 804(b)(3). As an initial matter, the parties agree that Brandon was unavailable within the meaning of Rule 804(b) due to his invocation of his Fifth Amendment privilege against self-incrimination. Nevertheless, Brandon’s statements that Gadson “should not be in it,” and that Brandon had not given Gadson two bags of cash, are not “truly self-inculpatory” for purposes of Rule 804(b)(3)(A) because they do not expose Brandon himself to criminal liability. Statements that “curry favor or deflect (or share) blame” do not fall within the scope of Rule 804(b)(3)(A). Hernandez v. Small, 282 F.3d 1132, 1141 n. 8 (9th Cir.2002). Further, while Brandon’s statement that he was the person who had put money in the garage at the Gillam Way house might have been self-inculpatory, the district court could have reasonably concluded that it was not supported by corroborating circumstances indicating its trustworthiness. In general, the exculpatory statements of family members “are not considered to be highly reliable,” LaGrand v. Stewart, 133 F.3d 1253, 1268 (9th Cir.1998); see also United States v. Pa-guio, 114 F.3d 928, 933 (9th Cir.1997), and therefore the close family relationship between Brandon and Gadson supports the district court’s determination that Brandon’s statements were not trustworthy. Further, the district court’s determination that Brandon’s testimony was “suspect” or unreliable was supported by testimony that he had made contradictory statements to the police and his co-conspirators. Gadson argues that there was sufficient evidence corroborating Brandon’s statement that he had put the $38,000 in the Gillam Way garage. Specifically, he cites the testimony from a downstairs tenant to the effect that someone named “Brandon” had previously lived in the apartment, and that the garage was usually unlocked. This slight evidence does not make the district court’s decision to disallow Brandon’s statement “illogical, implausible, or without support in inferences that may be drawn from facts in the record,” Hinkson, 585 F.3d at 1251. Accordingly, the district court’s decision not to admit the three statements at issue was not an abuse of discretion. Nor did the exclusion of Brandon’s statements deprive Gadson of his constitutional right to present a defense. The Supreme Court has held that “[a] defendant’s right to present relevant evidence is not unlimited, but rather is subject to reasonable restrictions,” and the exclusion of evidence is unconstitutional “only where it has infringed upon a weighty interest of the accused.” United States v. Scheffer, 523 U.S. 303, 308, 118 S.Ct. 1261, 140 L.Ed.2d 413 (1998). When the excluded evidence does not bear “persuasive assurances of trustworthiness” and is not “critical to the defense,” Chía v. Cambra, 360 F.3d 997, 1003 (9th Cir.2004), its exclusion does not violate a defendant’s due process rights, see United States v. Fowlie, 24 F.3d 1059, 1069 (9th Cir.1994) (rejecting a due process challenge to evidence excluded under Fed.R.Evid. 804(b)(3) because the statement lacked any “significant indicia of reliability” and was “tangential at best”); cf. Chambers v. Mississippi 410 U.S. 284, 302, 93 S.Ct. 1038, 35 L.Ed.2d 297 (1973) (holding unconstitutional an application of evidentiary rule that precluded the admission of a confession of guilt by a third party, where the testimony was directly exculpatory and bore “persuasive assurances of trustworthiness”). In this case, Brandon’s three statements do not have any “persuasive assurances of trustworthiness” and do not constitute critical exculpatory evidence, such as “someone else’s admissions of guilt.” Fowlie, 24 F.3d at 1069. Given Brandon Haynes’s unreliability and the substantial evidence establishing that Gadson was involved in the drug transactions at the Fouts and Gillam Way houses, exclusion of Brandon’s three statements did not violate Gadson’s due process rights. B We next turn to Gadson’s argument that the district court erred in admitting the government’s dog sniff expert testimony without holding a Daubert hearing. At trial, the government sought to introduce testimony from Investigator Joshua Moore, whose dog Marley gave positive alerts for the presence of narcotics when presented with several bundles of cash found at Gadson’s house and on his person. Before testifying to the jury, Investigator Moore testified extensively during voir dire about his experience and his dog’s training and reliability in the field. Investigator Moore and Marley were certified as a K-9 team in June 2010. Investigator Moore testified that he had been a canine handler since May 2010 and had received four-and-a-half weeks of training. Marley had been trained by another officer to detect marijuana, heroin, cocaine, and methamphetamine. According to Investigator Moore, Marley had practiced in a variety of training scenarios to ensure that he was reliably detecting the presence of various odors rather than simply associating them with one specific set of circumstances. The police department logs showed that Marley had a reliability rating of 100 percent in the field and had made only one potential false positive alert. Investigator Moore also noted the limits to Marley’s abilities: while he could detect the presence of four different drugs, he was unable to distinguish between individual drugs, and so an alert as to a pile of cash would indicate only that it had at some point been near one or more of those four drugs. At the conclusion of the voir dire, the court ruled that Investigator Moore and Marley were “adequately trained and experienced to testify, to give an opinion that possibly could assist the jury in some way” and overruled Wilson’s objection that the canine evidence was inadmissible without a Daubert hearing. On appeal, Gadson claims that dog sniff evidence is inherently unreliable and based on junk science. In making this argument, Gadson relies on various studies and reports indicating that dog sniff errors may be caused by handler cueing and errors, or may arise because drug dogs alert to residual odors and to compounds that are not unique to contraband. See, e.g., Richard E. Myers II, Detector Dogs and Probable Cause, 14 Geo. Mason L.Rev. 1, 14-16, 21-24 (2006); Lisa Lit, Julie B. Schweitzer, and Anita Oberbauer, Handler Beliefs Affect Scent Detection Dog Outcomes, 14 Animal Cognition 3 87 (2011). According to one expert cited by Gadson, a dog alert is insufficient to establish probable cause in a criminal case due to a high error rate. Myers, supra, at 14-16. In light of this evidence, Gadson argues that Investigator Moore’s testimony was not enough to demonstrate reliability, and the district court should have conducted a full hearing (as opposed to a voir dire) on the reliability of the dog sniff evidence. We review the district court’s decision to admit expert testimony for abuse of discretion. Mukhtar v. Cal. State Univ., Hayward, 299 F.3d 1058, 1063 (9th Cir.2002), as amended 319 F.3d 1073 (9th Cir.2003), overruled in nonrelevant part by Estate of Barabin v. AstenJohnson, Inc., 740 F.3d 457, 467 (9th Cir.2014) (en banc). Under Rule 702 of the Federal Rules of Evidence, “[a] witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion,” provided the testimony meets certain criteria. Rule 702 also requires “the trial judge [to] ensure that any and all scientific testimony or evidence admitted is not only relevant, but reliable.” Daubert v. Merrell Dow Pharms., Inc., 509 U.S. 579, 589, 113 S.Ct. 2786, 125 L.Ed.2d 469 (1993). Although the district court must perform a gatekeeping function, a trial court “not only has broad latitude in determining whether an expert’s testimony is reliable, but also in deciding how to determine the testimony’s reliability.” Mukhtar, 299 F.3d at 1064. The inquiry into whether the testimony is sufficiently reliable is “a flexible one.” United States v. Alatorre, 222 F.3d 1098, 1102 (9th Cir.2000). A separate pretrial hearing on reliability is not required, and a voir dire procedure can be sufficient. Id. at 1102-05 The Supreme Court has largely disposed of Gadson’s argument that dog sniff evidence is inherently unreliable. In Florida v. Harris, the Supreme Court held that the Florida Supreme Court erred by imposing an unnecessarily strict standard for evaluating whether the alert of a drug detection dog provided probable cause to search a vehicle. — U.S. -, 133 S.Ct. 1050, 1056-57, 185 L.Ed.2d 61 (2013). According to Harris, a court can conclude that a “dog performs reliably in detecting drugs” based on the dog’s training, test results, field history, and other case-specific facts. Id. at 1057-58. For example, “evidence of a dog’s satisfactory performance in a certification or training program can itself provide sufficient reason to trust his alert,” although a defendant must be given the “opportunity to challenge such evidence of a dog’s reliability.” Id. at 1057. This conclusion disposes of Gad-son’s claim that dog sniff evidence is per se unreliable because it is based on “junk science.” Moreover, Harris did not suggest that a district court had to perform a full-fledged Daubert hearing to determine whether the dog sniff testimony was sufficiently reliable to establish probable cause. Id. at 1056-58. Rather, the Court held that both the state and the defendant can proffer evidence relating to the dog’s reliability, and the court can “then evaluate the proffered evidence to decide what all the circumstances demonstrate. If the State has produced proof from controlled settings that a dog performs reliably in detecting drugs, and the defendant has not contested that showing, then the court should find probable cause.” Id. at 1058. A district court considering whether evidence of a dog alert is admissible under Rule 702 can undertake a similar evaluation. Here, Gadson had ample opportunity to cross-examine Moore, “contest the adequacy of a certification or training program,” or raise “circumstances surrounding a particular alert” that undercut Marley’s reliability. Id. at 1057. This was sufficient to satisfy the district court’s gatekeeping function, and the court did not abuse its discretion in declining to do more. Given Harris’s determination that a dog’s alert that meets certain reliability requirements may be sufficient to “make a reasonably prudent person think that a search would reveal contraband or evidence of a crime,” id. at 1058, we conclude that a dog’s alert that meets such requirements is also sufficiently reliable to be admissible under Rule 702.. Under the standard enunciated in Harris, the evidence regarding the reliability of Marley’s alert was more than adequate. Investigator Moore gave extensive testimony regarding his and Marley’s training and certification. He also testified regarding Marley’s reliability rating of 100 percent in the field. The defendants did not proffer evidence to the contrary. Accordingly, the district court did not abuse its discretion in admitting evidence of Marley’s alert. C We now consider Wilson’s claim that the district court erred by admitting the recordings of the prison phone calls made by Gadson and Wilson to third parties because the tapes had not been properly authenticated in violation of Rule 901 of the Federal Rules of Evidence. Wilson further claims that Officer Thompson’s testimony was insufficient to support a finding that the voices on the tapes belonged to the defendants. Because neither Gadson nor Wilson challenged the authentication of the tapes themselves at trial, we review this claim for plain error. See United States v. Lindsey, 684 F.3d 541, 550-51 (9th Cir.2011). Plain error is “(1) error, (2) that is plain, (3) that affect[s] substantial rights,” and “(4) the error seriously affect[s] the fairness, integrity, or public reputation of judicial proceedings.” United States v. Cotton, 535 U.S. 625, 631, 122 S.Ct. 1781, 152 L.Ed.2d 860 (2002) (alteration in original, internal citations and quotations marks omitted). Wilson did challenge the district court’s decision that the government put forth sufficient evidence that the voices on the tapes belonged to Gadson and Wilson, and so we review that determination for abuse of discretion. See United States v. Yin, 935 F.2d 990, 994 (9th Cir.1991). Under Rule 901(a) of the Federal Rules of Evidence, in order “[t]o satisfy the requirement of authenticating or identifying an item of evidence, the proponent must produce evidence sufficient to support a finding that the item is what the proponent claims it is.” In other words, the party offering the evidence must make a prima facie showing of authenticity “so that a reasonable juror could find in favor of authenticity or identification.” Yin, 935 F.2d at 996 (internal quotation marks omitted). The item may be authenticated by extrinsic evidence, id. at 995, such as through testimony of a knowledgeable witness, Fed.R.Evid. 901(b)(1). Thus, where the government offers an audiotape, a witness with knowledge may testify that the recording is what it purports to be, or is a true and accurate copy of the original. See United States v. Panaro, 266 F.3d 939, 951 (9th Cir.2001); United States v. Mouton, 617 F.2d 1379, 1383-84 (9th Cir.1980). Where the government offers a tape recording of the defendant’s voice, it must also make a prima facie case that the voice on the tape is in fact the defendant’s, whether by means of a witness who recognizes the voice or by other extrinsic evidence. United States v. Torres, 908 F.2d 1417, 1425 (9th Cir.1990). Once the offering party meets this burden, “the probative value of the evidence is a matter for the jury.” United States v. Workinger, 90 F.3d 1409, 1415 (9th Cir.1996). The district court does not abuse its discretion in admitting evidence that meets the minimum requirements for authentication. Id. at 1416. Here, Officer Thompson testified that he was familiar with the prison telephone system and gave detailed testimony regarding how the system recorded all calls, how the jail call log could be searched based on date, phone bank, and telephone number, and how he had run such searches many times. He testified that he reviewed more than 100 hours of prison phone calls relating to Gadson and Wilson. Although Officer Thompson did not testify that the calls introduced at trial were accurate copies of the prison recordings, neither defendant challenged the recordings on this basis. Officer Thompson’s testimony was “sufficient to support a finding that the item is what the proponent claims it is,” Fed.R.Evid. 901(a), and the district court did not err in failing to raise this issue sua sponte. Nor did the district court abuse its discretion in concluding that the government had carried its burden of making a prima facie case that the voices on the tapes were those of Gadson and Wilson. Officer Thompson testified as to the methodology he had used to identify the speakers. He first listened to recordings of all phone calls made from the cell wing in the prison where the defendants were held during the applicable time period and scanned those calls for context clues suggesting the identity of the speaker. Officer Thompson identified Gadson’s voice on the recording based on several factors: he had met Gadson and was familiar with his “very unique” voice, he determined that almost all of Gadson’s calls were to Ga-briella Haynes, and in at least one conversation, Officer Thompson heard Gadson talking about a list of items which had been seized from his house during the search, information accessible to only a handful of people at that time. Officer Thompson identified Wilson’s voice in the recording based on other extrinsic evidence. First, Officer Thompson heard the voice of a different prisoner calling Gabriella Haynes shortly after Wilson was admitted. Because the other defendants had previously been detained, Officer Thompson reasonably inferred that this new voice belonged to Wilson, the last member of the drug operation to be arrested. Second, during the time Wilson was in the segregation unit, he had to make written requests to use the telephone, and the timing of Wilson’s requests corresponded with the new voice’s calls to Gabriella Haynes. Finally, the caller discussed facts particular to Wilson’s case. Officer Thompson sufficiently narrowed the universe of possible callers so as to support an inference that the speakers in these calls were Gadson and Wilson. Cf. Yin, 935 F.2d at 996; Torres, 908 F.2d at 1425. Because the district court’s admission of this testimony was not “illogical, implausible, or without support in inferences that may be drawn from facts in the record,” Hinkson, 585 F.3d at 1251, it did not abuse its discretion in admitting it. Ill We next consider Wilson’s multiple arguments regarding the district court’s admission of Officer Thompson’s testimony regarding the recorded phone calls. A Because the sound quality of the tape recordings was poor, Wilson claims that Officer Thompson was acting as a government-produced transcript of the recordings, and the court did not take the necessary steps to ensure the accuracy of the transcript or interpretation. Because neither defendant raised this claim at trial, we review it for plain error. See Lindsey, 634 F.3d at 550-51. Applying this standard, we conclude the district court did not plainly err. Officer Thompson’s testimony regarding the context of the phone calls and interpretation of ambiguous or vague statements was not akin to a verbatim transcript of the calls, and thus the district court did not commit plain error in not considering sua sponte whether sufficient steps were taken to ensure the statements’ accuracy. Cf. United States v. Armijo, 5 F.3d 1229, 1234 (9th Cir.1993) (considering various factors regarding the accuracy of a transcription translating recorded telephone calls from Spanish to English). Moreover, even under the standard applied to written transcripts, there were ample indicia of accuracy, given that defense counsel had the opportunity to challenge the accuracy of Officer Thompson’s testimony and to introduce alternative versions, and the district court informed the jury on at least three occasions that the calls, not Officer Thompson’s testimony, were the evidence. See id. Nor did Wilson establish that the district court plainly erred in admitting the tapes on audibility grounds. “A recorded conversation is generally admissible unless the unintelligible portions are so substantial that the recording as a whole is untrustworthy.” United States v. Lane, 514 F.2d 22, 27 (9th Cir.1975). Wilson has not shown that the tapes were so uniformly unintelligible that the recordings should not have been presented to the jury. No objection was made at trial on this basis. Nor was there evidence “that persons in the courtroom were unable to hear substantial portions of the conversations recorded on the tapes, or that the words were unintelligible.” United States v. Tisor, 96 F.3d 370, 377 (9th Cir.1996). Further, Wilson waived or forfeited this argument by opposing efforts to provide the original recordings to the jury during their deliberations. When the jury requested the original telephone recordings (rather than the courtroom recordings of the clips as they were played during the trial), Wilson objected to giving the jury the original clips. Although the government proposed to give the jury “the clearest possible version” of the clips played at trial, Wilson argued against various approaches suggested by the government that, would have enabled the jury to hear the originals, and contended that the jury should be limited to the recording of what was played in court. Consequently, the district court’s failure to sua sponte exclude the tapes was not plain error. B Second, Wilson asserts that the district court erred in allowing Officer Thompson to testify concerning the content of the telephone calls. Wilson claims this type of testimony is inadmissible because it does not meet the criteria for lay opinion testimony under Rule 701 of the Federal Rules of Evidence. According to Wilson, Officer Thompson’s testimony was inadmissible under this rule because Officer Thompson was not a percipient witness to the conversations, his testimony was based on the investigation as a whole, his interpretation of vague testimony usurped the jury’s role as trier of fact, and his interpretation of one phone call relied on hearsay. Our consideration of Wilson’s arguments requires us to examine the scope of Rule 701. Rule 701 allows a lay witness to offer opinions that are (a) “rationally based on the witness’s perception,” (b) “helpful” to the jury, and (e) “not based on scientific, technical, or other specialized knowledge within the scope of’ expert testimony. When promulgated in 1975, this rule represented a departure from the then-prevailing evidentiary principles governing lay witness testimony, which generally required witnesses “to limit their testimony just to the facts they perceived and avoid opinions or inferences based on those facts.” 29 Charles Alan Wright & Victor James Gold, Federal Practice & Procedure § 6251, at 105 (1997). Courts justified this approach on the grounds that “lay-witness opinion usurps the role of the jury, whose job it is to draw conclusions as to the meaning of the evidence,” and because “testimony limited to perceived facts was considered more reliable than mere opinion, which could be misleading.” Id. § 6252, at 109. The drafters of Rule 701 rejected both these distinctions. First, the distinction between “fact” and “opinion” proved to be unworkable in practice. See Fed.R.Evid. 701 advisory committee’s note (noting “the practical impossibility of determining by rule what is a ‘fact’ ” and that “[witnesses often find difficulty in expressing themselves in language which is not that of an opinion or conclusion”); see also United States v. Pierson, 503 F.2d 173, 176 (D.C.Cir.1974) (stating that the “so-called opinion rule” was “not strictly followed — due in large part to the difficulty of drawing a fine distinction between fact and opinion”). Indeed, as the D.C. Circuit explained, “[tjhere is no conceivable statement however specific, detailed and ‘factual,’ that is not in some measure the product of inference and reflection as well as observation and memory.” Pierson, 503 F.2d at 176 (quoting McCormick on Evidence § 11 (1972)). The drafters of Rule 701 also rejected the concern that lay opinion testimony would mislead juries. Rule 701 assumes instead that “the natural characteristics of the adversary system will generally lead to an acceptable result,” and weaknesses in the lay witness’s testimony can be emphasized through “cross-examination and argument.” Fed.R.Evid. 701 advisory committee’s notes; see also United States v. Beck, 418 F.3d 1008, 1015 (9th Cir.2005) (noting that “direct and cross-examination of a lay witness testifying as to his or her opinion is relied upon to verify the accuracy of the testimony”). In applying Rule 701 to the lay opinion testimony of law enforcement officers, we have held that an officer’s interpretation of intercepted phone calls may meet Rule 701’s “perception” requirement when it is an interpretation “of ambiguous conversations based upon [the officer’s] direct knowledge of the investigation.” United States v. Freeman (Kevin Freeman), 498 F.3d 893, 904-05 (9th Cir.2007); see also United States v. Simas, 937 F.2d 459, 464-65 (9th Cir.1991) (finding no abuse of discretion in admitting officers’ lay testimony “concerning their understanding of what [defendant] meant to convey by his vague and ambiguous statements”). In Kevin Freeman, for instance, we held that once the government established a foundation, a police officer could provide lay witness opinion testimony regarding the meaning of statements in the defendant’s intercepted phone calls because the testimony was based on the officer’s “direct perception of several hours of intercepted conversations — in some instances coupled with direct observation of [the defendants] — and other facts he learned during the investigation.” 498 F.3d at 904-05; see also United States v. El-Mezain, 664 F.3d 467, 513-14 (5th Cir.2011) (allowing lay opinion testimony interpreting telephone calls when “the agents’ opinions were limited to their personal perceptions from their investigation of this case”); United States v. Rollins, 544 F.3d 820, 830-33 (7th Cir.2008) (finding no error in the district court’s decision to allow the agent’s testimony regarding his “impressions” of recorded conversations when the testimony was “based on the agent’s perceptions derived from the investigation of this particular conspiracy”). Such testimony is admissible even if the testifying officer was not a participant in the recorded conversation. Kevin Freeman, 498 F.3d at 904; see also United States v. Jayyousi, 657 F.3d 1085, 1102 (11th Cir.2011) (holding that a lay witness’s testimony was admissible even though “he did not personally observe or participate in the defendants’ conversations”); United States v. Garcia, 994 F.2d 1499, 1507 (10th Cir.1993) (admitting an officer’s opinion based only “on listening to the conversations between coconspira-tors”). Lay witness testimony regarding the meaning of ambiguous conversations based on the witness’s direct perceptions and experience may also prove “helpful to the jury” for purposes of Rule 701. See Kevin Freeman, 498 F.3d at 904-05 (agent’s “understanding of ambiguous phrases” based on the “direct perception of several hours of intercepted conversations” along with “direct observation” of defendants and “other facts he learned during the investigation” resulted in testimony that “proved helpful to the jury in determining what the [co-conspirators] were communicating during the recorded telephone calls”); see also Rollins, 544 F.3d at 832-33 (agent’s testimony based on listening to every intercepted conversation, and other “personal observations and perceptions” related to the specific case at issue “assisted the jury in determining several facts in issue”). On the other hand, an officer’s testimony interpreting recorded conversations may fall outside the scope of Rule 701 if it is not based on the witness’s perception (for example, if it is based on speculation or hearsay) or is not helpful to the jury. Kevin Freeman, 498 F.3d at 905. Lay testimony is not helpful to the jury if it merely provides “ ‘interpretation of dear statements’ ” that are within the common knowledge of the jury. Id. (quoting United States v. Dicker, 853 F.2d 1103, 1109 (3d Cir.1988)). In Dicker, for instance, a government agent testified about the meaning of recorded conversations, and explained that the parties to the conversation were discussing means for obtaining “phony paperwork.” 853 F.2d at 1106. But the recorded conversations themselves did not include any discussion of phony paperwork, and there was no indication “that the documents to be obtained were not to be genuine.” Id. at 1105. Under these circumstances, Dicker held that the officer’s mischaracterization of the plain words used in the conversation was not helpful to the jury, and thus barred by Rule 701. Id. at 1108-10; see also United States v. Freeman (Marcus Freeman), 730 F.3d 590, 597 (6th Cir.2013) (holding that Rule 701 barred an officer’s testimony which essentially “spoon-fed his interpretations of the phone calls and the government’s theory of the case to the jury, interpreting even ordinary English language”); Rollins, 544 F.3d at 833 (admitting an agent’s “impressions” regarding an intercepted conversation because the agent “was not merely telling the jury what result to reach as to the defendants’ culpability”). As the drafters of Rule 701 noted, “meaningless assertions which amount to little more than choosing up sides” should be excluded for lack of helpfulness. Fed.R.Evid. 701 advisory committee’s note. In addition, testimony that relies on or conveys hearsay evidence, such as when an officer relies on the truth of a third party’s statement as the basis for an interpretation of a statement in an intercepted phone call, is also inadmissible, both because it would not be based on the officer’s own perceptions, and would not be helpful. Kevin Freeman, 498 F.3d at 905. Any error in admitting lay opinion testimony under Rule 701, however, could be harmless if in light of the evidence as a whole, there was a “fair assurance that the jury was not substantially swayed by the error.” Id. (internal quotation marks omitted). A minority of circuits have construed Rule 701 much more narrowly and barred officers from interpreting intercepted communications based on their review of the recordings and personal involvement in an investigation. Thus in United States v. Hampton, 718 F.3d 978 (D.C.Cir.2013), the D.C. Circuit determined that a district court had violated Rule 701 by allowing an FBI agent to testify regarding intercepted conversations, even though the government established that the FBI agent had been in charge of the investigation, monitored wiretaps, performed physical surveillance, supervised other agents who monitored the wiretaps, and had reviewed each of the 20,000 conversations intercepted by the wiretaps. Id. at 981-83. According to the D.C. Circuit, such testimony raised a risk that the agent “was testifying based upon information not before the jury” and the jury “had no way of verifying his inferences or of independently reaching its own interpretations.” Id. at 983 (internal quotation marks omitted); see also United States v. Grinage, 390 F.3d 746, 750-51 (2d Cir.2004) (same). We disagree with this approach, which harkens back to the evidentiary policies that were rejected by the drafters of Rule 701. A lay witness’s opinion testimony necessarily draws on the witness’s own understanding, including a wealth of personal information, experience, and education, that cannot be placed before the jury. If witnesses cannot draw on their experience and knowledge, they are effectively limited to presenting factual information. Such an approach echoes the now-abandoned distinction between allowing testimony regarding “facts” but not “opinions,” and revives the historical policy that admitting lay opinion testimony usurps the role of the jury, a view that was rejected by the Rule 701 drafters. See Hampton, 718 F.3d at 983; id. at 986 (Brown, J., concurring); Grinage, 390 F.3d at 749-51. Rule 701 does not impose such a limitation. Under Rule 701, while the district court must exercise its discretion wisely to minimize problems that may arise in admitting lay opinion testimony, see Albertelli, 687 F.3d at 447 (listing dangers and safeguards), the guiding policy of the Rule is to trust the jury to identify unreliable opinion testimony with the help of the adversary process, see Fed.R.Evid. 701 advisory committee’s note. Courts regularly admit lay opinion testimony regarding the identity of a person in a photograph, see, e.g., Beck, 418 F.3d at 1014-15, and voice identification testimony, see, e.g., United States v. Thomas, 586 F.2d 123, 133 n. 23 (9th Cir.1978), even though the witness provides such identification based on past contacts with the pertinent individual that are outside the jury’s knowledge. Similarly, an investigator who has accumulated months or even years of experience with the events, places, and individuals involved in an investigation necessarily draws on that knowledge when testifying; indeed, it is those out-of-court experiences that make the witness’s testimony helpful to the jury. Contrary to the rationale of Hampton and Grinage, “the application of Rule 701 should not be influenced by concern that opinion testimony usurps the role of the jury or that factual testimony is more reliable than opinion testimony.” Wright, supra, § 6252, at 112. We now consider Wilson’s arguments in light of these principles. “The admissibility of lay opinion testimony under Rule 701 is committed to the sound discretion of the trial judge and his decision will be overturned only if it constitutes a clear abuse of discretion.” Nationwide Transp. Fin. v. Cass Info. Sys., Inc., 523 F.3d 1051 (9th Cir.2008) (quoting United States v. Yazzie, 976 F.2d 1252, 1255 (9th Cir.1992)). Because Wilson did not challenge Officer Thompson’s testimony under Rule 701 at trial, we review for plain error. See Lindsey, 634 F.3d at 550-51. 1 First, Wilson argues that Officer Thompson could not offer his interpretations of the recorded phone conversations under Rule 701, because lay opinion testimony is admissible only when a witness was a party to the conversation himself or was a percipient witness. Because we rejected this precise argument in Kevin Freeman, 498 F.3d at 904-05, the district court did not plainly err in not striking Officer Thompson’s testimony on this ground. 2 Next, Wilson claims that Officer Thompson’s interpretation was inadmissible because it was based on the investigation as a whole, including the police report and information contributed by other officers, rather than merely his personal observations. The district court did not plainly err in failing to strike Officer Thompson’s testimony on this ground. According to his testimony, Officer Thompson had been involved in the investigation of the drug conspiracy since early 2010. His involvement spanned the searches of the Fouts house, the multi-day surveillance of the Gillam Way house, the search of the Gillam Way house, and the review of around 100 hours of prison phone calls. In light of our decision in Kevin Freeman, where we admitted testimony based on similar experiences, the district court had ample grounds to conclude that Officer Thompson based his interpretations on his personal knowledge of facts he learned during the investigation. In arguing against this conclusion, Wilson relies on Marcus Freeman, in which the Sixth Circuit held that an agent’s testimony was not admissible under Rule 701 because it was based solely on the agent’s review of 23,000 phone conversations, rather than on the agent’s involvement in the investigation. 730 F.3d at 596-99. The facts of Marcus Freeman are quite different from our case, however. In Marcus Freeman, the government conceded that the testifying agent “lacked the first-hand knowledge required to lay a sufficient foundation for his testimony under Rule 701(a).” Id. at 597. Because the agent had not been involved in the surveillance of the defendant, and had not observed “any activity relevant to interpreting the calls,” the agent relied solely on “the general knowledge of the FBI and the investigation as a whole.” Id. at 596. Nor did the agent shed light on the meaning of ambiguous statements based on personal knowledge regarding the investigation; rather the agent essentially “spoon-fed his interpretations of the phone calls and the government’s theory of the case to the jury, interpreting even ordinary English language.” Id. at 597. Under these circumstances, the agent’s testimony was not “rationally based” on his own concrete perceptions regarding the investigation and was not helpful to the jury, as required by Rule 701. Here, by contrast, Officer Thompson had the requisite personal experience and knowledge of the investigation, had reviewed the phone calls in the context of that knowledge, and did not merely regurgitate the government’s theory of the case. Because the government established a foundation for Officer Thompson’s testimony, while such a foundation was fatally lacking in Marcus Freeman, Marcus Freeman has little bearing on Wilson’s claims. 3 Along the same lines, Wilson argues that the district court erred in not sua sponte striking Officer Thompson’s interpretation of Wilson’s reference to “Powell” to mean “Joe Powell,” and his interpretation of Wilson’s references to “Donte” and “they have him on tape” to mean the police had Donte Edwards on tape. Wilson argues that this interpretation of vague testimony usurps the jury’s function. We disagree. Officer Thompson’s testimony was based on his knowledge of the investigation and the persons involved, evidence that was also before the jury. Because a jury may become confused by vague pronouns such as “who,” “him,” and “that,” Officer Thompson’s testimony would provide helpful context. See Kevin Freeman, 498 F.3d at 900, 902 (holding that an officer’s interpretation of “ambiguous statements consisting of ordinary terms,” like “that” was admissible as lay opinion testimony). The dissent highlights a particular conversation, where Wilson stated “ ‘You know, he’s the one’ ‘ — referring to the informant Pitka — ’ ‘that started this shit.’ ... ‘That time with Batman, that was him.’ ” Dissent at 1231. At trial, Officer Thompson explained that “Batman” refers to Brandon Haynes, and Wilson’s statement “that time” refers back to the November 2010 incident (in which Officer Thompson was involved) where Pitka executed a controlled buy from Brandon which led to Brandon’s eventual arrest. As the dissent recognizes, id., Officer Thompson’s testimony that “Batman” was Brandon’s nickname is precisely the type of investigation-specific opinion testimony that Kevin Freeman authorizes. But contrary to the dissent, id., Officer Thompson’s explanation of “that time” is likewise admissible, because Kevin Freeman permits “interpretations of ambiguous conversations based upon [the officer’s] direct knowledge of the investigation,” 498 F.3d at 904-05. For instance, Kevin Freeman approved of the officer’s interpretation of the statement, “Man, it’s done already” to mean “he’s given the cocaine to Kevin Freeman and that he’s received his money for it.” Id. at 902. According to Kevin Freeman, such interpretations “did nothing more than offer one possible framework for understanding the conversation.” Id. Officer Thompson’s testimony regarding his interpretation of “that time” falls comfortably within the same range of interpretive testimony. At the very least, it was not plain error for the district court to allow the testimony. Indeed, the dissent advances no reason why the district court’s failure to cut off Officer Thompson’s testimony sua sponte was “clear” or “obvious” error, United States v. Olano, 507 U.S. 725, 734, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993) (internal quotation marks omitted), in light of our settled law allowing this type of testimony. 4 We next turn to Gadson’s hearsay challenge to the admissibility of Officer Thompson’s testimony characterizing statements made by Brandon Haynes. As we have explained, lay opinion testimony may not convey or rely on hearsay, because it is not helpful to the jury. Kevin Freeman, 498 F.3d at 905. During Officer Thompson’s testimony about one of the prison phone calls, he noted that Wilson was reading off of a portion of the [police] report that we made after interviewing Brandon Haynes. You hear Brandon Haynes ... in the background ... [say] “Hell, no.” One thing we learned throughout this investigation is that in different phone calls [Brandon Haynes] made numerous denials to everyone, even though we had a video-recorded, audio-recorded interview with Mr. Haynes where he made these admissions to us. Gadson’s counsel made a hearsay objection to “the purported admissions of Brandon Haynes,” but the district court implicitly denied the objection. According to Gadson, Officer Thompson’s statement that Brandon “made these admissions to us” is hearsay that is not admissible under any exception. We disagree. Officer Thompson’s statement that Brandon “made these admissions to us” does not meet the definition of hearsay: a statement that is offered “to prove the truth of the matter asserted in the statement.” Fed.R.Evid. 801(c)(2). Officer Thompson did not testify as to the nature of “these admissions,” repeat any assertion made by Brandon, or suggest that the jury should consider any admission made by Brandon to be truthful. Rather, Officer Thompson mentioned Brandon’s admissions to the police as context for the recorded phone call, and to explain why the jurors would hear Brandon state “Hell, no” in the background. A witness making statements to provide clarification and context for other statements is not offering evidence for the truth of the matter asserted, and such testimony does not run afoul of any hearsay prohibition. See United States v. Collicott, 92 F.3d 973, 981 n. 7 (9th Cir.1996); see also United States v. Whitman, 771 F.2d 1348, 1352 (9th Cir.1985) (no error where informant’s recorded statements were only offered “to show that they were made,” and to put the statements in context, rather than for their truth). Accordingly, the district court did not abuse its discretion in declining to strike this testimony. 5 Finally, Wilson argues that the district court erred in allowing Officer Thompson to provide his interpretation of drug jargon such as “nine of leaded” (crack cocaine), or “a strap” (firearm), because he had not been qualified as an expert witness. Because- neither Gadson nor Wilson objected at trial to the drug jargon testimony as impermissible expert testimony, we review this claim for plain error. See United States v. Pino-Noriega, 189 F.3d 1089, 1097 (9th Cir.1999). “[L]aw enforcement testimony about the meaning of drug jargon may be both expert and lay testimony, depending on the circumstances.” United States v. Reed, 575 F.3d 900, 922 (9th Cir.2009). Unlike a lay witness, a witness who is an expert on drug jargon may interpret encoded drug terms even if the witness had not been involved in that particular investigation. See id. And so police officers’ testimony regarding drug terms related to an investigation may be expert opinion testimony, lay opinion testimony, or both. Although we have noted the difficulties that may arise when an agent qualified as an expert also provided lay testimony, see Kevin Freeman, 498 F.3d at 903-04, we have nevertheless held that such dual use of “case agents as both expert and lay witnesses is not so inherently suspect that it should be categorically prohibited.” Id. at 904. Our concerns regarding a witness who qualifies as an expert giving lay opinion testimony are not directly applicable when an agent who is providing lay testimony also interprets a few drug terms in the context of discussing personal observations. While witnesses who testify as an expert may receive “unmerited credibility” for their lay testimony, because expert testimony is “likely to carry special weight with the jury,” id. at 903 (internal quotation marks omitted), the converse is not true: a lay witness’s testimony carries no special weight, even if at points the lay witness has recourse to relevant background and training. Similarly, there is no special risk that lay testimony regarding firsthand observations would be merely speculative. Cf. id. at 904. We have also expressed concern that because expert witnesses may opine on matters about which they have no personal knowledge, they may also rely on inadmissible hearsay when providing lay testimony. Id. Such a danger does not necessarily arise when lay witnesses are testifying about matters in which they were involved. Here, Officer Thompson testified primarily as a lay witness providing his firsthand knowledge of the case; he referenced his reliance on training and police experience (as opposed to familiarity with the individuals through the specific investigation) only when defining the single term “nine of leaded.” This isolated instance does not raise the concerns identified in Kevin Freeman. Further, the district court could reasonably conclude that Officer Thompson encountered the two terms at issue in the context of his investigation as well as through his training and experience. See Reed, 575 F.3d at 922. “Because the distinction between lay and expert testimony in this context is a fine one, we do not fault the district court for failing to intervene sua sponte.” Kevin Freeman, 498 F.3d at 904. We also reject Wilson’s argument that Officer Thompson’s reference to police reports, or to his use of special equipment to review the tapes, gave him an unwarranted aura of special knowledge. Wilson did not raise this argument at trial, and the district court did not plainly err in not addressing sua sponte this concern. C Both defendants object to a specific portion of Officer Thompson’s testimony in response to questioning by Wilson’s attorney. After Officer Thompson had testified regarding the recorded prison phone calls, Wilson’s attorney engaged him in the following colloquy: [Wilson’s attorney]: [Nonetheless, when we come into the life or come into the courtroom, wherever we go, we bring our own position and biases with us. [Officer Thompson]: I would agree. [Wilson’s Attorney]: Right. So you would have a tendency to project a police officer’s interpretation onto things? [Officer Thompson]: I would — I would state yes, that I think I put a — a—good case together, and I’m confident of the people charged in the case are guilty of the crimes. Gadson’s counsel objected to Officer Thompson’s answer on the ground that it constituted vouching. The district court did not strike the answer, but stated before the jury: “[ultimately it’s up to the jury to determine guilt or innocence, and so the jury should consider all the evidence presented in that regard.” On appeal, Gadson renews his argument that Officer Thompson’s statement constituted impermissible vouching because it was Officer Thompson’s personal opinion of the defendants’ guilt. Wilson joins this argument, and also argues that Officer Thompson’s opinion was improper because it went to the ultimate issue of the defendants’ guilt, in violation of Rule 704(b) of the Federal Rules of Evidence. Prosecutors may not place “the prestige of the government behind a witness through personal assurances of the witness’s veracity, or suggesting that information not presented to the jury supports the witness’s testimony.” United States v. Necoechea, 986 F.2d 1273, 1276 (9th Cir.1993). By putting an unwarranted imprimatur of credibility or authority on the testifying witness, a prosecutor may “jeopardize the defendant’s right to be tried solely on the basis of the evidence presented to the jury.” United States v. Weatherspoon, 410 F.3d 1142, 1146-48 (9th Cir.2005) (internal citations omitted). In this case, however, the government did not elicit Officer Thompson’s testimony, nor did it vouch for his credibility “either by putting its own prestige behind the witness, or by indicating that extrinsic information not presented in court supports the witnesses] testimony.” United States v. Garcia-Guizar, 160 F.3d 511, 520 (9th Cir.1998) (internal quotation marks omitted). Rather, Officer Thompson testified only that he was confident about his own t