ORDER AMENDING OPINION AND DENYING PETITION FOR REHEARING
The opinion filed on September 29, 1992, is amended as follows:
[Editor’s Note: Amendments have been incorporated within published opinion.]
[1455]*1455Judges Kozinski and Leavy have voted to deny the petition for rehearing and to reject the suggestion for rehearing en banc. Judge Poole has voted to grant the petition for rehearing and to accept the suggestion for rehearing en banc.
The full court has been advised of the suggestion for rehearing en banc, and no judge of the court requested a vote on the suggestion for rehearing en banc. Fed. R.App.P. 35(b).
The petition for rehearing is denied and the suggestion for rehearing en banc is rejected.
OPINION
LEAVY, Circuit Judge:
This criminal action involved the government’s contention that the defendants were engaged in an international high level drug trafficking conspiracy in Bolivia and Mexico. The conspiracy was uncovered as part of a “sting” operation of the Drug Enforcement Agency (DEA) and the U.S. Customs. The seven defendants, whose appeals are consolidated,1 are Mexican and Bolivian citizens who were arrested and charged by the United States Government with a host of conspiracies involving controlled substances 2 and the use of a communications facility to facilitate the commission of a controlled substance offense. The superseding indictment that was handed down in the United States District Court for the Southern District of California contained twenty-one separate counts.
In opening remarks at the trial, the government stated:
For the next month or so, you are going to hear a story about a search, a search that is going to take us on a five-thousand mile journey, a search, a journey from the cliffs of La Jolla, to the jungles of Bolivia; and the search, ladies and gentlemen, is for one thing: cocaine.
This journey involves a plan that had one objective, one mission. That was to find the mother lode of cocaine in Bolivia, the source. This is a journey to the source, the source for the cocaine.
Reporter’s Transcript (RT) II at 148-49.
Despite this statement, no drugs were ever recovered in Bolivia and none were introduced into evidence at trial. No one testified that any drugs were ever recovered in the possession of any of the defendants. Only one person tied the defendants to cocaine and cocaine laboratories discovered in the Bolivian jungle region known as the Beni. That person was a government informant by the name of David Wheeler. Wheeler was unescorted by any government undercover agent when he went to Bolivia.
Wheeler first came to the attention of the authorities in August of 1986 when he was arrested and charged in Oklahoma for possession of one kilogram of cocaine. Wheeler pleaded guilty. While incarcerated, Wheeler told the arresting agents that he was interested in cooperating with the government. He also wrote several letters soliciting contact with the government.
In January of 1987, as a result of Wheeler’s solicitations, U.S. Customs Agent Joe Robles met with Wheeler and debriefed him. Wheeler claimed he could lead Customs to high level Mexican government officials who were trafficking drugs into the United States. Wheeler claimed, from his many years of illegal drug dealing in Mexico, to know either Mexican government officials or people who were connected with them. Wheeler was released on bond and allowed to make telephone contact with certain individuals in Mexico. Ultimately, this led to the government’s sting [1456]*1456operation and the arrest and trial of the defendants.
At trial, the government maintained that the Bolivian defendants, Ayala, Vargas-Bruun, and Roman-Salas, represented a Bolivian drug cartel that produced massive amounts of cocaine. RT II at 162. The government said it would prove that Giron, Brumel, and Carranza, the Mexican defendants, were necessary players in the drug operation, id., because they allegedly arranged for protection for the airplane that would carry the cocaine from Bolivia when it made a refueling stop in Mexico. The government stated it would prove that these defendants were policemen or members of the military in Mexico with high level connections. RT II at 163-64. The government also stated:
The government will prove that Hector Brumel and Jorge Carranza, because of their association and their position in Mexico, were able to ... provide the security [for the airplane][.] And the government will prove that Pablo Giron, Hector Brumel and Jorge Carranza ... associated themselves with, or secured the patronage of General Poblano Silva, who is responsible, at the time, for the military sector, similar to a state, south of Mexico City, the military sector or zone called Puebla.
The government will prove that Pobla-no Silva assigned to that association of people, a man named Lieutenant Colonel de la Vega. Number Two in command.
With the assurance of General Silva and Lieutenant Colonel de la Vega, ladies and gentlemen, Louis [the main undercover operative who was posing as a member of the Mafia] was going to get the protection he sought.
RT II at 164-65.
The trial lasted from January 5, 1989, until April 26, 1989. On May 25, 1989, the jury returned its verdict of guilty for all defendants on each count except one, which the government dismissed.
On appeal, the defendants argue that material information bearing on the credibility of David Wheeler was withheld from them in violation of Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963), and the Jencks Act, 18 U.S.C. § 3500. We reverse and remand for a new trial.
DISCUSSION
Standard of Review
We have not employed a single standard of review where there have been challenges to a conviction based on a Brady violation. At various times our review has been de novo. See United States v. Lehman, 792 F.2d 899, 901 (9th Cir.), cert. denied, 479 U.S. 868, 107 S.Ct. 232, 93 L.Ed.2d 158 (1986); United States v. Kennedy, 890 F.2d 1056, 1058 (9th Cir.1989), cert. denied, 494 U.S. 1008, 110 S.Ct. 1308, 108 L.Ed.2d 484 (1990); United States v. Pisello, 877 F.2d 762, 764 (9th Cir.1989); accord United States v. Monroe, 943 F.2d 1007, 1012 (9th Cir.1991) (“In general, a district court’s ruling on the prosecution’s duty to produce evidence under Brady is reviewed de novo.”). At other times we have reviewed for clear error, see United States v. Strifler, 851 F.2d 1197, 1201-02 (9th Cir.1988), cert. denied, 489 U.S. 1032, 109 S.Ct. 1170, 103 L.Ed.2d 228 (1989), and explained that this standard is appropriate where some, but not all, of a document has been produced. United States v. Monroe, 943 F.2d 1007, 1012 (9th Cir.1991). Our opinion in Monroe also suggests that there might be occasions where review for an abuse of discretion would be appropriate. Id. at 1012 n. 3. We observe that other discovery-related decisions are reviewed under the abuse of discretion standard. See United States v. Boshell, 952 F.2d 1101, 1104 (9th Cir.1991) (denial of Jencks Act request); United States v. Sanchez, 908 F.2d 1443, 1451 (9th Cir.1990) (refusal to require disclosure of confidential informant’s identity).
We need not decide which standard of review applies here. Given the facts of this case, under any standard we would conclude that the Levine Memorandum contains exculpatory material that must be released to the defendants.
[1457]*1457A district court’s denial of a motion to produce a witness’ statement pursuant to the Jencks Act, 18 U.S.C. § 3500(b), is reviewed for an abuse of discretion. United States v. Augenblick, 393 U.S. 348, 355, 89 S.Ct. 528, 533, 21 L.Ed.2d 537 (1969). A conviction will be affirmed if the “Jencks error is more than likely harmless.” United States v. Wallace, 848 F.2d 1464, 1470 (9th Cir.1988).
I. The Levine Memorandum
The government’s main witness was David Wheeler. In opening remarks, Assistant U.S. Attorney Stephen Nelson stated:
Now, ladies and gentlemen, David Wheeler is not the only witness in this case; but he is an important witness in that he, and the government will prove this, is the key to unlocking the door that led to the Mexicans and the Bolivians.
David Wheeler was a key, and that key had to be put in the lock and turned; and if the cuts on the key weren’t right, the lock wouldn’t open, so the agents tested them.
RT II at 160. David Wheeler was so central to the government’s case at the end of the trial that the government argued in closing:
If David Wheeler never went to the stash, never saw the cocaine, never unwrapped the package and that’s a figment of his imagination, then you, ladies and gentlemen, should acquit all of the Bolivian defendants and Mr. Mendez-Duenas also; but I do believe that — but I submit to you, the evidence is to the contrary.
RT XXXV at 5918.
David Wheeler had been involved in illegal drug operations for twenty-five years prior to his arrest in Oklahoma. He testified he very often lied and convinced individuals that he was someone he was not. He testified that he had worked as a screenwriter and had connections in Hollywood. The government portrayed Wheeler as someone who “had a very sordid past” yet could be believed in this case:
It’s like a doctor who’s convicted of a serious felony, and he goes to prison.... When he goes to prison, while in prison, he does research and solves the cancer riddle ... [i]s he a good man or a bad man? He’s a man, ladies and gentlemen. He’s a complex individual. At one time, he did good things. At one time, he did bad things.
You can’t generalize. You have got to look at the man and the situation. That’s what I am asking you to do here.
I am asking you to go beyond the name calling and the character assassination, and to zero in on David Wheeler[.]
RT XXXVII at 6255-56.
In final arguments, the government discredited the defendants’ attempts to impugn Wheeler’s credibility. The government argued:
David Wheeler agreed to put it on the line. He went undercover. He exposed himself to great danger. He went down into Mexico, with no backup, no gun, no radio. He went down to Bolivia, went out into the Beni, met Winston Rodriguez and Pato Pizarro, the defendants in this case.
He went out to see the labs and the cocaine. He was grilled by Pato Pizarro. He was grilled by Winston Rodriguez.
[I]f David Wheeler hasn’t passed the test, David Wheeler would not have come back from Bolivia.
David Wheeler was like an astronaut. Floating, at the third space station. When he was in Bolivia, the only link he had was a commercial phone link with George Urquijo up in San Diego.
... David Wheeler was acutely aware of what he was looking at and the dangers involved. Is Dave Wheeler a saint? No. Is David Wheeler a choir boy? No. Is he going to get the Nobel Peace Prize? No. He assuredly is not.
You don’t have to like David Wheeler; but, ladies and gentlemen, I suggest, when you look at all of the facts, his role in this case, you have to acknowledge that what he did took a lot of courage; [1458]*1458and no amount of name calling and character assassination can alter that fact.
RT XXXVII at 6251-53.
On appeal, the defendants contend that the government withheld crucial information bearing on Wheeler’s credibility. After the trial, the defendants became aware of a government memorandum written by Michael Levine (the “Levine Memorandum”), a retired Drug Enforcement Agency Group Supervisor and a witness for the government. That memorandum, which was directed to Special Agent James Collier of the Office of Professional Responsibility, was highly critical of Wheeler’s integrity and role during the course of the undercover investigation.
Two months before trial the government moved, ex parte, for a protective order regarding the Levine Memorandum and related materials. The trial court reviewed the documents and agreed that the Levine Memorandum should be sealed. The defendants were given a six-page redacted version of the original forty-two page report.3 Previously, they had been given a seven page report prepared by Levine on December 29, 1987, entitled “Undercover Negotiations for Attempted Purchase of 1,000 Kilograms of Cocaine,” which was attached to the Levine Memorandum for the ex parte proceeding. The government contended at the proceeding that the forty-two page report was merely an “editorialized or amplified” version of the seven page report prepared on December 29, 1987.
After we heard oral argument in this appeal, the government released the entire Levine Memorandum and attachments to the defendants. We ordered supplemental briefing from the parties on what effect, if any, the withholding of this information had on the defense.
We conclude that the withholding of the Levine Memorandum and related documents violated the defendants’ right to due process under the rule of Brady v. Maryland, 373 U.S. 83, 87, 83 S.Ct. 1194, 1196, 10 L.Ed.2d 215 (1963), which provides that exculpatory material in the government’s possession must be released to criminal defendants.4 Evidence impeaching the testimony of a government witness falls within the Brady rule when the reliability of the witness may be determinative of a criminal defendant’s guilt or innocence. Giglio v. United States, 405 U.S. 150, 154, 92 S.Ct. 763, 766, 31 L.Ed.2d 104 (1972). We also conclude that the withholding violated the Jencks Act, which entitles a defendant to access to government documents for assistance in cross-examination of witnesses in order to impeach for prior inconsistent statements.
II. Analysis
Assistant U.S. Attorney Stephen G. Nelson, in an affidavit dated November 4, 1988, in support of the “Government’s Motion For A Protective Order and Request for Ex Parte In Camera Review Of Certain Intra-Agency Confidential Reports And Statements Pursuant to Rule 16(d)(1), Federal Rules Of Criminal Procedure And Sealing Order Thereon,” justified sealing the Levine Memorandum largely on grounds of irrelevancy:
After reviewing the enclosed intra-agen-cy confidential materials, it is the Gov[1459]*1459ernment’s position that as to the [material requested to be sealed], these reports or statements ... are not Jencks Act ... statements since they are not witness statements that relate to the subject matter of Agent Levine’s direct testimony. Similarly, it is the Government’s position that these materials do not fall within the definition or application of [Brady ] or its progency inasmuch as the materials consist primarily of the gratuitous opinions or comments of one individual agent [i.e., Agent Levine], who for whatever reasons: 1) is highly critical of certain of his DEA and Customs colleagues whom he considers inept or incompetent; 2) does not like, believe or trust David Wheeler, the Customs informant; 3) feels the case was at least to some degree botched; and 4) is concerned about DEA being embarrassed or its image harmed because the informant became aware, during the course of the undercover operation, of DEA’s institutional or personnel shortcomings. While Agent Levine’s opinions, feelings, and conclusions might make for an interesting “insider’s expose” on the Government’s “WAR ON DRUGS” or a sensational-type newspaper article, it is respectfully submitted that [Brady does not ] require disclosure of such judgmental-type observations.
(Emphasis added.)
Upon review, we conclude that the Levine Memorandum is more than simply an internal DEA memo and it is far from irrelevant. The memorandum contains a detailed and specific description of Wheeler’s conduct during the course of the investigation, including his false claims to government agents about his high-level business and banking connections in the Cayman Islands; his , formal recantation of statements he made to Customs and DEA agents about buying information from and bribing DEA agents in Florida; and his thwarting of an attempt to tape a telephone conversation with a Mexican general who allegedly was involved with the defendants in the drug operation. The memorandum also describes Wheeler’s influence and control over the government investigation of this case. In Levine’s words, from his memorandum:
I noticed that when the Customs officers were talking about [Wheeler], it was almost as if they were in awe of him. They were eccstatic [sic] at the results of his cooperation to that point....
[Customs undercover agent] Urquijo later confided in me that he often found himself pitted between his “bosses” (who preferred to follow Wheeler’s suggestions) and me. He also stated that, with his experience in internal affairs, he was very “uncomfortable” with the latitude and freedom the informant had been given, but being a new agent in customs ... he had felt often “trapped” in his role.
Levine Memorandum at 2. Levine continued:
[T]here was much uncotrolled [sic] telephone contact between WHEELER and the violators [some of the defendants]. He often, without consulting or coordinating with the DEA control agent ... or myself, would speak to the violators telling them, “Luis said ...” Thus utilizing my undercover identity to manipulate the case the way he (Wheeler) saw fit. Weeks later I had to overcome many statements he attributed to “Luis” (my undercover identity). He was constantly allowed to operate in this fashion throughout the investigation unless I was present. I made it clear, when I was present, that it was a drug case and that I was a DEA agent, and that it would be done my way — which Wheeler never ceased to fight against.
Levine Memorandum at 5 (emphasis added). Levine clarified that
The points of the various arguments [with Wheeler] were usually not as important as the control they signified. The issue was that the Cl [the confidential informant, Wheeler] was out of control, in that he believed himself on an equal par with the investigating agents. Being an “outsider” in a case that was [1460]*1460essentially the responsibility of San Diego DEA and Customs, I still did not think it my place to “rein him in.”
Levine Memorandum at 8.5
At trial, the defendants presented the defense that they were not drug dealers, but that they had plotted a “reverse sting;” that is, that they planned to take the money but not supply the drugs (what the government refers to as the “we’re not drug dealers we’re thieves” defense). They presented evidence that they were not who they had represented themselves to be to the undercover agents; i.e., Mexican officials or members of the militia or police, and that they did not have high-level connections. In closing arguments, they maintained that Wheeler’s testimony that they were in fact drug dealers was not believable and that the government should not have been taken in by his stories:
During the whole time, showing the extent of the government’s foolish, foolish, foolish and undoubtedly well-intentioned trust in this man, during the whole time he was on his own recognizance ... he’s never supervised- He was taken, at his word, by the government.
[Millions of dollars are talked about but not one speck of cocaine shows up at any time and not one sample is gathered by the government and nothing really is seen except, surprise, surprise, surprise, that which Mr. Wheeler says he saw_
The Government, the individuals involved in this case, through their trust and through their misguided confidence [in Wheeler], ignored by choice or by lack of wisdom points throughout this whole investigation that if they had been reviewed under even the most glancing of considerations would have revealed that this was all a scam.
RT XXXVI at 6015-17.
The defendants also made the following insightful arguments:
What is incredible is that this man was essentially placed in charge of the investigation. We have ten, 15 agents milling around in the background, but the person who led this investigation throughout it was a convicted criminal who had not [had] verified any of the truths that supposedly he had told the government.
RT XXXVI at 6012.
We have Mr. Wheeler, and unfortunately in this screenplay of a case Mr. Wheeler was producer, director, screenwriter and actor. Not one of the agents involved in this case really supervised what this man did.
RT XXXVI at 6055.
In rebuttal, Assistant U.S. Attorney Nelson argued the very issue whose evidence he withheld on the ground that it was irrelevant:
Now, defense counsel would have you believe that, and somehow everything David Wheeler said was taken at face value. Not true. Agent Robles debriefed Wheeler for days. He became satisfied that David Wheeler knew what he was talking about....
Now, does that mean that Agent Robles set out an investigation where David Wheeler would have free rein or run the investigation as counsel said? Absolutely not.
That’s why you have videotaped meetings. That’s why you have audio taped meetings and telephone calls. That’s why you have other agents usually present.
That’s why you have diagrams, maps, and photographs, and the other corroborative evidence.
[1461]*1461RT XXXVII at 6250-51 (emphasis added). Yet, by persuading the court to seal most of the Levine Memorandum on grounds that it was irrelevant, Nelson withheld the very evidence that would have contradicted his own argument.
The Brady Violation
Brady information includes “material ... that bears on the credibility of a significant witness in the case.” United States v. Strifler, 851 F.2d 1197, 1201 (9th Cir.1988), cert. denied, 489 U.S. 1032, 109 S.Ct. 1170, 103 L.Ed.2d 228 (1989). Under Brady, the prosecutor’s withholding of evidence favorable to the accused violates due process where the evidence is material either to guilt or innocence. United States v. Gordon, 844 F.2d 1397, 1403 (9th Cir.1988). Favorable evidence includes impeachment evidence. Id. at 1402.
To prove a Brady violation the defendant must show failure to disclose material evidence. Evidence is material if “there is a reasonable probability that, had the evidence been disclosed to the defense, the result of the proceeding would have been different.” United States v. Bagley, 473 U.S. 667, 682, 105 S.Ct. 3375, 3383, 87 L.Ed.2d 481 (1985).
There is no doubt the information in the Levine Memorandum is material. Faced with the evidence that Wheeler allegedly was running the investigation and was therefore in a position to manipulate Customs, the DEA, the defendants, and the evidence, the jury might well have thought the government’s arguments incredible that Wheeler was reliable in this investigation. The jury might have focused more on the arguments that tended to show that Wheeler might have lied about what he saw in Bolivia and that he was able to locate the cocaine laboratories from a surveillance by a DEA aircraft the day before the raid with the Bolivian Leopardos. See RT XXXVI at 6053-54 (“Although it was unsaid by Mr. Wheeler, [that is the secret] why he was able to so easily and cavalierly and with no effort whatsoever to find [the cocaine laboratories], to find a speck of dust in a vastless jungle.”).
That the verdict might have been different is especially true where the evidence showed that Wheeler alone thwarted the opportunity to tape a telephone call to a General Poblano Silva in Mexico, who the government maintained was responsible for the military sector called Puebla and would arrange protection for the cocaine shipment when the airplane refueled in Mexico. The defendants argued in closing:
Agent Levine, as Luis ... orders Carranza to call the general. “I want to hear; I want to listen in on the other line. I want you to call the general. I want to hear that everything is okay between the two of you.” Very specific.
Call the general; and what happens? Although Mr. Carranza is specifically told to call the general, he calls somebody named Pablo Lopez, who nobody has ever heard of, remember, Levine said: “I have no idea who he was.”
And they say virtually nothing in this phone conversation; and then he gets off the phone and makes some excuse about not being able to call the barracks or the base or something; and everybody buys it.
No one says, “wait a minute, we told you to call the general. Who’s Pablo Lopez?” Nothing.
They buy the Carranza calls, however.
But the point is that Carranza was specifically told to call the general. He couldn’t because there was no general to call.
Nobody suspicious, nobody cares, ... but this fact is glossed over by the prosecution because it doesn’t fit. It doesn’t fit.
Now, Mr. Nelson implies that the reason nobody met, saw, spoke with, or even received the written communication from the general, is because ... [t]his is his words, “[the General was able] to insulate himself so well in this case.”
There is not one iota of evidence, not one shred of evidence, that any general ever had anything to do with this case, [1462]*1462other than Carranza and Brumel’s words [when they were engaged in the reverse “sting.”]
RT XXXVII at 6202-04.
Had the defendants had the Levine Memorandum, however, they could have argued based on the following scenario:
[D]uring this final undercover operation and the resultant arrests, he (Wheeler) was able to prevent the government from obtaining what may turn out to be one of the most important bits of evidence in the whole investigation.... It was known that Caranzas [sic] was working for a “General Silva,” the man actually in charge of the zone in Mexico, where our contraband laden plane was due to land for refueling: however, we had no direct evidence connecting Silva to the conspiracy.
On 1/7/88 in a meeting at San Diego Customs ... I suggested that a Title III be obtained for the undercover house, so that I might “manipulate” the Colonel [Carranza] into calling General Silva and we would have a recorded conversation of the General’s voice.
At approximately 11:30 [on January 13, 1988], in a hastily called meeting at the undercover house ... Wheeler tells me that the Colonel had called the General from Las Vegas to explain the delays and that the General had been livid and hung up on him after accusing him of stealing his money and burning him. Wheeler further stated that the Colonel had asked that he not tell Luis (me) about it.
I thought the stage was now set perfectly for me to call an emergency meeting with the Mexicans and demand that the General be called. We had nothing to lose.... Wheeler was against this for various vague reasons, none of which made much sense. It seemed to me that for some unknown reason he simply did not want the U.S. Government to obtain a recorded conversation with this general. The argument went on for some time, exclusively between myself and the Cl.
Finally, ... I stepped out of my role of undercover and ordered Wheeler to contact the Mexicans and tell them “Luis wants an emergency meeting.”
Wheeler, when he saw he had no backing among the Customs agents, stated that the only time you could get the General at home was at night. I then told him to call the meeting for that evening then.
At 4:pm, I received a call from S/A Doug Hebert telling me that there was not going to be a meeting; that the Mexicans wanted to go to Sea World and that Wheeler was taking them there, after which they would go to bed early and meet Luis in the morning. Hebert was unclear as to who had authorized the Cl to do this. He stated that he was with Robles and that Robles had gotten a call and that “that was what the call was about.” Hebert went on to state that we would have a better chance getting the General on the phone in the morning[.]
I reminded Hebert that Wheeler had stated that the only time you could get the General at home was at night. I further told him that the Cl had successfully blocked DEA from getting a recording of the General and that the Cl was doing anything he wanted and was totally “uncontrolled.”
Levine Memorandum at 28-29; 33-34.
We agree with the defendants that
The information in the Levine Memorandum indicating that Wheeler deliberately thwarted Levine’s attempt to tape record a telephone conversation with the General is critically important. The defense in this case maintained that defendants Carranza, Brumel and Giron’s claims to be acting on behalf of Mexican Army General Poblano Silva were totally false, and that in fact, no one from the Mexican military had actually promised to provide protection. Wheeler’s actions in deliberately acting contrary to Levine’s instructions to bring the defendants to an undercover meeting so that a telephone call [1463]*1463to the General could be made give rise to the suspicion that Wheeler knew or suspected that there was no General to call.
Supplemental Brief at 5. Yet, despite withholding the memorandum, Nelson argued in closing that “Jorge Carranza ... was needed and essential because he’s your linkage to that airstrip and to Poblano Silva[.]” RT XXXY at 5875.
There is “a reasonable probability that the suppressed ... evidence affected the verdict,” United States v. Gillespie, 852 F.2d 475, 481 (9th Cir.1988), in that “had [this] evidence been disclosed to the defense, the result of the proceeding would have been different.” Bagley, 473 U.S. at 682, 105 S.Ct. at 3383. Wheeler’s credibility as a witness was an important issue in the case. Evidence that he lied during the investigation, that he had had an undue influence on the DEA and Customs agents involved in the investigation, or that he thwarted the opportunity to gather crucial evidence, would be relevant to his credibility and the jury was entitled to know of it. See Giglio, 405 U.S. at 154-55, 92 S.Ct. at 766.
Agent Robles might have been impeached with the memorandum as well. In response to the government’s question, Agent Robles testified:
Q. During the two-and-a-quarter years you have been working with David Wheeler in the conduct of this investigation, has he ever said or done anything that has caused you to change your opinion as to his reliability, truthfulness, and cooperation in this case?
A. Not at all.
RT VI at 877.
The defendants argued in closing that Robles had been honestly mislead:
Mr. Robles, as honest and as good a man as he may be, does not, maybe never had a point of reference or capacity to gauge whether Mr. Wheeler was telling the truth about anything.
RT XXXVI at 6005. The Levine Memorandum, however, reveals that Robles knew of Wheeler’s false claims and his recantation of having bribed or bought off DEA agents in Miami: Robles was present during the interview where Wheeler recanted his statements about the bribes. Moreover, Robles knew that Wheeler had disobeyed a direct order by preventing Carranza’s call to General Poblano Silva, because he was present at the meeting where Levine ordered that the call be placed, and Robles got and passed on to Special Agent Hebert the information that Wheeler was taking the Mexican defendants to Sea World instead. See Levine Memorandum at 33, 34.
We reject the government’s argument that, because the defendants’ collective defense refocused the inquiry to their state of mind and credibility instead of Wheeler’s, the government’s failure to provide the entire Levine Memorandum and its attachments obviates any Brady argument. We also reject the government’s argument that the Levine Memorandum contained merely cumulative evidence. In truth, it contained evidence contradictory to the government’s position. The jury, not the prosecutor, “has the duty to sift through the inconsistencies of testimony, to weigh the credibility of witnesses and to resolve any ambiguities in the evidence.” Saint Paul, Marine Transp. Corp. v. Cerro Sales Corp., 505 F.2d 1115, 1119 (9th Cir.1974) (civil case). If provided with the Levine Memorandum and related documents, the defendants “might very well have chosen not to put on an affirmative defense at all, but rather, to rely on cross-examination of Agent Levine, David Wheeler, and other government witnesses to establish that Wheeler had lied about ... crucial aspects of this case.” Appellants’ Supplemental Brief at 14.
The Jencks Act
The withholding of the Levine Memorandum and its attachments also violates the Jencks Act. The Jencks Act requires the government to produce any written statements by a government witness that relate to the subject matter of any direct testimony by the witness. 18 U.S.C. § 3500(b). “The rationale of the Jencks Act is to provide the defense with material that could impeach a government witness.” [1464]*1464United States v. Polizzi, 500 F.2d 856, 893 (9th Cir.1974).
The Jencks Act defines a statement as “a written statement made by said witness and signed or otherwise adopted or approved by him.” 18 U.S.C. § 3500(e)(1). The Levine Memorandum is clearly a “statement” within this definition. Levine felt so strongly about his perceptions of Wheeler and of the investigation in general that he prepared the memorandum and further, called U.S. Attorney Nelson to inform him about it some four months before trial. Nelson Affidavit, para. 4.
In his affidavit, Nelson stated that the Levine Memorandum was “not Jencks Act ... statements since they are not witness statements that relate to the subject matter of Agent Levine’s direct testimony.” We disagree. “The prosecution is obligated to disclose to the defense statements falling within the Jencks Act regardless of anyone’s perception of the utility of the statements for impeachment.” Polizzi, 500 F.2d at 893. Moreover, it is sufficient that, “ ‘[i]n determining whether the statements in question ‘related to’ the direct testimony of the witness, it must relate generally to the events and activities testified to.’ ” United States v. O’Brien, 444 F.2d 1082, 1086 (7th Cir.1971) (quoted in United States v. Derrick, 507 F.2d 868, 871 (4th Cir.1974)).
The Levine Memorandum does relate “generally to the events and activities testified to.” In direct examination, Agent Levine was asked questions about, and translated, certain taped meetings with the defendants that are referred to in the Levine Memorandum (and which were part of the redacted material released to the defendants). See, e.g., RT VIII beginning at 1165 (the meeting with certain of the defendants on September 21, 1987, at the undercover house in La Jolla); RT XI beginning at 1879 (the trip to Panama and meeting with certain of the defendants starting on November 15, 1987). The meetings described in the Memorandum, however, are placed in the context of Levine’s perception of the investigation, and Wheeler’s role in it, while in direct testimony, there is no such context.
On direct examination, the government elicited from Levine his expertise in “sensing” situations and people:
Q. (by Mr. Nelson):
During your 24 years as an undercover agent, have you carried yourself, and comported yourself, and conducted yourself in a way that is, to some degree, dependent upon how you sense or interpret the background circumstances or intentions of the people with whom you are dealing?
A. Yes.
Q. And, in that role as an experienced undercover agent, you try, as best you can, to understand the thinking, as best you can, the thinking process of the other person so as to react in an appropriate manner?
A. That’s exactly what I am trying to do.
RT XI at 1931-32. Agent Levine’s descriptions in the memorandum of Wheeler, Wheeler’s role, and the undercover operation in general are presumably based on the same expertise he testified to on direct examination. Yet, when Levine was asked in cross-examination about the original report he had written, he obfuscated by stating “the [redacted version] is my original report, less the items that didn’t concern this case.” RT VIII at 1262. The Levine Memorandum, therefore, could have been used to impeach Levine when the taped meetings were described as if they were nothing but an ordinary undercover investigation and “sting.”
Wheeler’s signed recantation of his allegations about corrupt DEA agents, attached to the Levine Memorandum, is also a “statement” within the meaning of the Jencks Act. Wheeler could have been impeached with his statement because he claimed to be telling the truth during the course of the investigation and trial.
Because we conclude that the withheld evidence could have affected the outcome of the trial, the Jencks error was not “more [1465]*1465than likely harmless.” Wallace, 848 F.2d at 1470.
CONCLUSION
There “is a reasonable probability that had the [Levine Memorandum and attachments] been disclosed, the result of the proceeding would have been different such that [our] confidence in the outcome is undermined.” United States v. Lai, 944 F.2d 1434, 1440 (9th Cir.1991), cert. denied, — U.S. -, 112 S.Ct. 947, 117 L.Ed.2d 116 (1992).
REVERSED and REMANDED.