Opinion for the court filed by District Judge HAROLD H. GREENE.
Dissenting opinion filed by Circuit Judge TAMM.
HAROLD H. GREENE, District Judge:This is an appeal from a conviction of forgery, uttering, and possession of stolen mail matter. 18 U.S.C. §§ 495,1708. The only claim of error to merit extended discussion1 is that the jury, with prosecuto*801rial acquiescence, was given the erroneous information that at the time of appellant’s trial her alleged accomplice, a key witness against her, had already been sentenced for her participation in the criminal venture and therefore had nothing to gain from testifying for the government.
I
Since Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963), it has been clear that the prosecutorial suppression of evidence favorable to the accused, if material to guilt or punishment, is violative of due process, and that the government is affirmatively required to disclose all exculpatory materials. Moreover, both before and after Brady, in decisions now generally considered under the Brady rubric, the Court has held that a conviction obtained by the knowing use of perjured testimony violates the defendant’s right to a fair trial mandated by the due process clauses of the Fifth and Fourteenth Amendments. United States v. Agurs, 427 U.S. 97, 103, 96 S.Ct. 2392, 2397, 49 L.Ed.2d 342 (1976); Napue v. Illinois, 360 U.S. 264, 79 S.Ct. 1173, 3 L.Ed.2d 1217 (1959); Alcorta v. Texas, 355 U.S. 28, 78 S.Ct. 103, 2 L.Ed.2d 9 (1957); Pyle v. Kansas, 317 U.S. 213, 63 S.Ct. 177, 87 L.Ed. 214 (1942); Mooney v. Holohan, 294 U.S. 103, 55 S.Ct. 340, 79 L.Ed. 791 (1935). This rule applies both when the testimony relates directly to an essential element of the government’s proof and when it affects the credibility of a crucial witness. “The jury’s estimate of the truthfulness and reliability of a given witness may well be determinative of guilt or innocence, and it is upon such subtle factors as the possible interest of the witness in testifying falsely that a defendant’s life or liberty may depend.” Napue v. Illinois, supra, 360 U.S. at 269, 79 S.Ct. at 1177.2
In elaboration of these general rules, it is established that the prosecutor has an affirmative obligation to correct the record when a principal prosecution witness falsely claims that no promises of leniency were made, and that, should he fail to discharge that obligation, the defendant may be3 entitled to a new trial on due process grounds. See, e.g., Napue v. Illinois, supra, 360 U.S. at 264, 79 S.Ct. at 1173; Giglio v. United States, 405 U.S. 105, 92 S.Ct. 763, 31 L.Ed.2d 104 (1972); United States v. Barham, 595 F.2d 231 (5th Cir. 1979); Boone v. Paderick, 541 F.2d 447 (4th Cir. 1976); United States v. Pope, 529 F.2d 112 (9th Cir. 1976).
Compliance with these principles in this case demanded that the prosecutor set the record straight when the principal prosecution witness falsely adduced facts which led the jury to believe that she could not possibly derive gain from her testimony against appellant.
II
The evidence against appellant indicated that on May 10,1978, she assisted one Susan Johnson in cashing a stolen, forged government check at the American Security and Trust Bank. There was ample proof that Johnson stole and forged the check,4 and that appellant was present at and facilitated the cashing. The principal contested issue before the jury was whether appel*802lant’s participation5 was accompanied by the requisite criminal intent, or whether, as she claimed, she was duped into assisting Johnson with an illegal check-cashing transaction wholly conceived and implemented by the latter. On that issue, Johnson’s testimony differed sharply from that given by appellant.
Appellant testified at trial that she merely assisted Johnson in cashing a check at a bank where appellant had a friend because Johnson herself did not have a bank account, and that she did not know that the check was stolen. Johnson, on the other hand, stated that she fully discussed the true status of the check with appellant, and that the latter assisted her in the expectation of receiving part of the proceeds. According to Johnson, she showed appellant the check, appellant stated that she knew a teller who might be able to cash it, and arrangements were made to meet the following day to complete the transaction. Johnson stated that she did sign the check at the bank in the presence of appellant6 and after cashing it gave appellant $400 to divide with another accomplice.
Thus, Johnson’s credibility was critical. In an effort to test that credibility, appellant’s counsel cross-examined her regarding the status of the criminal charges against her arising out of the check-cashing incident, as follows:
“Q. You were — you haven’t been sentenced in that case, have you?
A. Yes, I have.
Q. When were you sentenced?
A. The 28th.
Q. Of October?
A. Yes.
Q. What sentence did you receive?
A. I received three months’ supervision. After three months, I have to go back in front of the judge that sentenced me. It was Judge Gesell. If I went by the requirements of the Court, that I could have my probation transferred to Michigan.” 7
The witness’ claim that she had already been sentenced was untrue. In fact, she pleaded guilty on September 20, 1978, and her sentencing was deferred from October 27, 1978, to January 15, 1979, that is, from four weeks before appellant’s trial to six weeks after that trial.8 Her false statements had the inevitable effect of leading the jury to the erroneous conclusion that she could not gain from cooperating with the government and that her testimony was therefore unlikely to be tainted by an improper pro-government bias.9 Yet, the *803prosecutor, who knew or should have known10 the actual facts, remained silent, and he did nothing to alert the Court and jury to the truth. In our view, that failure to correct the witness’ misrepresentations was improper and warrants a new trial.
In practical experience, few, if any, factors are more likely to induce an accused to testify, possibly falsely, against another, than the expectation of prosecutorial or sentencing leniency.11 Jurors are not unaware that an alleged accomplice who has not yet been charged or sentenced is susceptible to direct or indirect pressure to cooperate with the government and that his testimony should therefore be considered with special caution. United States v. Thorne, 174 U.S.App.D.C. 57, 527 F.2d 840 (1975); Stith v. United States, 124 U.S.App.D.C. 81, 361 F.2d 535 (1966). One who has already been sentenced is of course immune to this kind of pressure. For that reason when, in the context of an exploration of the issue of possible leniency in return for cooperation, a witness falsely claims that he has already been sentenced, the claim and its falsity are as damaging to the defendant’s due process rights as would be a false assertion that no promise of leniency was ever made. In the one instance the witness’ false claim is that he has not been given or promised consideration by the government; in the other that he cannot be given such consideration.
The record here does not affirmatively show whether Johnson was promised by the prosecution that her cooperation would be brought to the attention of the sentencing judge.12 As it turned out, while the prosecutor did not, in fact, recommend leniency when Johnson was finally sentenced after appellant’s trial, neither did he press for a stiff sentence in spite of her criminal record. Moreover, and more significantly, we do not and cannot now know what the effect on the prosecutor and the sentencing judge would have been had Johnson failed *804or refused to testify against appellant.13 The vice in the prosecutor’s silence lay precisely in its preclusion of an exploration of this and similar issues.14
Only by being apprised that Susan Johnson was still facing sentencing could the jury have a rational basis for deciding whether her persistent efforts to assign a share of the culpability to appellant were the product of a desire to tell the truth or an effort to ingratiate herself with the prosecutor, the sentencing judge, or both. Because the misinformation provided by the witness and the silence of the prosecutor15 deprived the jury of the opportunity to make its own judgment concerning Johnson’s credibility, it seriously flawed the proceedings.16
Our conclusion regarding the prosecutor’s obligation in these circumstances is further buttressed by the fact that at the outset of the appellant’s trial defense counsel alerted the Court and the prosecutor to his belief that Johnson would give false testimony. Counsel correctly asserted that numerous inconsistencies existed between the statement the witness gave to law enforcement officials and her grand jury testimony as well as between that testimony and the evidence she was expected to give at trial,17 and for that reason he requested that she be prohibited from testifying. The trial court rejected the request, stating that the *805possibility of perjury was inherent whenever the government relied on witnesses who had themselves been involved in the crime. Appellant argues that this ruling constitutes reversible error, but none of the cases cited18 supports that proposition. However, in view of that factual background, the prosecutor was obligated to exercise special care with respect to the conduct of his principal witness, and when that witness proceeded to misstate crucial facts concerning her own sentencing status, he had a clear duty to speak to correct the record.
Ill
We consider next whether the prosecution’s nondisclosure was sufficiently material to the jury’s determination of appellant’s guilt to require a new trial.
In United States v. Agurs, supra, the Supreme Court established general rules concerning the appropriateness of a new trial in nondisclosure cases. Dividing undisclosed evidence situations into several categories, it held with respect to cases in which the prosecution relies on testimony which it knows or should know to be false19 that the conviction must be set aside if there is “any reasonable likelihood that the false testimony could have affected the judgment of the jury.” United States v. Agurs, supra, 427 U.S. at 103, 96 S.Ct. at 2397.20
That is the situation here. The evidence against appellant consisted essentially of her own confession21 and of the testimony of the bank teller and that of Susan Johnson.
The confession alone was insufficient to prove guilt, for as a matter of law it could sustain a conviction only if supported by independent' evidence. Smith v. United States, 348 U.S. 147, 75 S.Ct. 194, 99 L.Ed. 192 (1954);22 Opper v. United States, 348 U.S. 84, 75 S.Ct. 158, 99 L.Ed. 101 (1954); Wong Sun v. United States, 371 U.S. 471, 83 S.Ct. 407, 9 L.Ed.2d 441 (1963). The teller’s testimony did not provide the necessary corroboration, for it did not bear on appellant’s intent and, to some extent at least, it actually supported appellant’s version of the events.23
*806Thus, the testimony of Johnson was crucial to intent and hence to guilt, for it constituted the only non-confession evidence to suggest that appellant knew that the check was stolen and would be forged and uttered. At a minimum — in the words of the Agurs standard — there was a reasonable likelihood that the testimony the witness gave could have affected the judgment of the jury. Since that testimony was false in a critical respect, the conviction cannot stand.
For these reasons, the judgment of. conviction is reversed and the case is remanded for a new trial.
Judgment accordingly.
. Appellant also claims that oral and written statements she gave at the police station should have been suppressed, that her motion for judgment of acquittal on the stolen mail charge should have been granted, and that the alleged accomplice should not have been permitted to testify at all. There is no merit to the first two contentions; the third is discussed in the text in the context of the principal claim.
Appellant’s claim with respect to her statements is based on Miranda v. Arizona, 384 U.S. 436, 86 S.Ct. 1602, 16 L.Ed.2d 694 (1966). The government contends, relying on Oregon v. Mathiason, 429 U.S. 492, 97 S.Ct. 711, 50 L.Ed.2d 714 (1977) that the investigators were not required to give appellant the Miranda warnings because she was not under arrest at the time of interrogation. We need not reach this issue because appellant was given Miranda warnings both orally and in writing, and she signed a form attesting to her understanding of these warnings. The district court did not credit her claim that she did not understand her rights and did not knowingly waive them, and there is nothing in the record to cause us to set aside that determination. Likewise, there is no basis for equating the questioning here with that in Mincey v. Arizona, 437 U.S. 385, 98 S.Ct. 2408, 57 L.Ed.2d 290 (1978). In that case, statements were obtained from the accused while he was in a hospital intensive care unit, seriously wounded, barely conscious, and totally isolated. This appellant was fully conscious and aware of the significance of the questioning, and able to leave at will, and there is no basis for concluding that the statements she made were not the “product of a rational intellect and free will.” 437 U.S. at 398, 98 S.Ct. at 2416.
Appellant’s claim of error with respect to the denial of her motion for judgment of acquittal on the charge of possession of stolen mail matter is based on the proposition that at the time the check was stolen it was not “in the mail” *801and thus could not form the basis for a conviction under 18 U.S.C. § 1708. However, it is clear that an item which is properly addressed but misdelivered by the postal authorities remains “in the mail” for section 1708 purposes when it is removed from a mail depository, even if the intent to steal is formed at a later date. United States v. Anton, 547 F.2d 493, 495-96 (9th Cir. 1976); United States v. Davis, 461 F.2d 83, 87-90 (5th Cir. 1972); United States v. Lavin, 567 F.2d 579 (3d Cir. 1977).
. The Court in Napue further noted that “[t]he same result obtains when the state, although not soliciting false evidence, allows it to go uncorrected when it appears.” 360 U.S. at 269, 79 S.Ct. at 1177.
. See Part III infra.
. The check, in the amount of $982.84, was made out to a third person, and Susan Johnson claimed to have found it in her own mailbox. She appropriated the check and subsequently cashed it under the circumstances described above.
. Appellant was essentially tried on the basis of being an accessory. Unlike Johnson, she was a first offender.
. The witness acknowledged that appellant did not handle the check at any time while inside the bank.
. Transcript at 126-27, United States v. Iverson, Crim.No. 79-1231 [hereinafter cited as Transcript], When defense counsel thereafter suggested to the witness that her sentencing had been deferred to January 15 of the following year, she kept insisting that she had a “probation officer ... [and had] to abide by certain ... regulations to the Court.” She added that she “had assumed that ... if I got probation ... I could go home and ... after this period of time I have got to go back in front of [the judge].” Transcript at 128.
. The trial was held November 27-29, 1978.
. Other incidents served further to mislead the jury in this regard.
Thus, Johnson stated that she had been expressly informed that she would receive no consideration for her cooperation with the government with respect to the charges against her, a claim that may also have been untrue. There is nothing in the record of Johnson’s two sentencing proceedings or her presentence report to support that claim (Record, United States v. Johnson, Crim.No. 78-457, D.D.C.), and it is hardly consistent with normal prosecutorial practice. See U.S. Department of Justice, Principles of Federal Prosecution, pp. 52-53 (1980). In fact, although Johnson had a record of four prior convictions and two arrests not resulting in convictions, and although the Probation Department recommended that she be incarcerated, the prosecution dismissed two out of the three charges against her, and the Court, without objection from the prosecution, suspended the imposition of sentence and granted her probation.
Again, when the Court asked Susan Johnson, “Didn’t the sentencing judge make it perfectly clear that whether you testified or not had *803nothing to do with whether you would get probation? He made that perfectly clear did he not?”, she replied in the affirmative. Actually, the sentencing judge had made no such commitment, as defense counsel pointed out at a subsequent bench conference (Transcript at 145, 150). The prosecutor again remained silent, and the jury never learned the true facts. His silence, under these circumstances, represents more than a failure “to correct testimony which an appellate court ... might view as misleading . ..see dissenting opinion at n. 2. The fact that it was the judge, and not counsel, who asked the rhetorical question could only reinforce the jury’s belief that Johnson had no incentive to secure appellant’s conviction.
In one sense, these several colloquies might imply to one well versed in criminal procedure that Johnson had not yet been sentenced. However, the dominant impression left with the jury was that sentencing had occurred prior to the trial. Indeed, the government itself still appears to believe at the present time that Johnson was sentenced before appellant’s trial rather than thereafter. Appellee’s brief, p. 18.
. The most minimal preparation would have disclosed to the prosecutor and defense counsel the sentencing status of the principal witness. See Giglio v. United States, 405 U.S. 150, 154, 92 S.Ct. 763, 766, 31 L.Ed.2d 104 (1972); American Bar Association Project on Standards for Criminal Justice, Standards Relating to the Prosecution Function and the Defense Function, § 4.1 (Approved Draft 1971). The record is unclear as to defense counsel’s understanding at trial. Compare transcript at 127-28 with id. at 150, 92 S.Ct. at 763. In any event, the prosecutor had an independent responsibility to alert the Court and jury to the truth. A prosecutor’s use of perjured testimony represents “not just . .. misconduct, but more importantly ... a corruption of the truth-seeking function of the trial process.” United States v. Agurs, supra, 427 U.S. at 104, 96 S.Ct. at 2397.
[Tjhough the attorney for the sovereign must prosecute the accused with earnestness and vigor, he must always be faithful to his client’s overriding interest that ‘justice shall be done.’ He is the ‘servant of the law, the twofold aim of which is that guilt shall not escape or innocence suffer.’
Id. at 110-11, 96 S.Ct. at 2400-2401.
. That is so especially where, as here, the individual has a criminal record, and cooperation with the wishes of the prosecution may mean the difference between probation and a sentence to imprisonment.
. Recognition of such cooperation is typically considered by judges in sentencing defendants (see, e.g., United States v. Rosenberg, 195 F.2d 583, 605-06 n.28 (2d Cir. 1952); Roberts v. United States, 445 U.S. 552, 100 S.Ct. 1358, 63 L.Ed.2d 622 (1980); ABA Standards — Pleas of Guilty, § 1.8(a)(v) and comment (Approved Draft 1968)).
. Nor can we know the witness’ state of mind at appellant’s trial, with her sentencing still to come, for that avenue of cross examination was effectively foreclosed by her assertion that she had previously been sentenced.
. Including the issue of whether, as Johnson asserted, an Assistant U.S. Attorney had informed her that her cooperation or lack of cooperation with the government with respect to appellant’s case would make no difference in the prosecution’s attitude toward her own sentence.
. The prosecutor not only did not at any time correct Johnson’s false testimony; he actually reiterated it in his closing argument, thereby compounding the prejudicial impact:
[The PROSECUTOR]: I would suggest to you the testimony [Susan Johnson] gave when she finally came in here, having pled guilty as she said to a five-year penalty was forthright, was just the way it happened.
Miss Johnson on the one hand at this point had nothing to lose. Her case is disposed of.
Transcript at 8, United States v. Iverson, Crim.No. 78-587 (D.D.C. Nov. 29, 1978).
. See United States v. Leonard, 161 U.S.App.D.C. 36, 494 F.2d 955, 963 (1974), where we said,
The permissible scope of exploration on cross-examination is not curtailed by the absence of explicit government promises of leniency, for the defense may attempt to show government ‘conduct which might have led a witness to believe that his prospects for lenient treatment by the government depended on the degree of his cooperation.’ United States v. Campbell, 426 F.2d 547, 549 (2d Cir. 1970). Jones might reasonably have surmised that there was some connection between his testimony in this case and the government’s offer, arriving as it did while he was waiting to testify in this case.15
15 The fact that Jones had received immunity neither detracts nor adds from our supposition as to the possible effect on Jones of the government’s offer. The point is that the jury, not an appellate court, should be permitted to make this determination on the basis of a thorough cross-examination.
The defendants were entitled to be given broad latitude in their effort to impeach the credibility of government witnesses on cross-examination. Alford v. United States, 282 U.S. 687, 51 S.Ct. 218, 75 L.Ed. 624 (1931).
See also, United States v. Pope, 529 F.2d 112 (9th Cir. 1976), where failure to disclose an agreement to testify resulted in a reversal even though the agreement in express terms it related only to the brother of the appellant. “It stretches credulity,” said the court, that the witness “would have believed that he could refuse to incriminate the appellant before the Grand Jury without jeopardizing his hopes for a light sentence.” 529 F.2d at 114.
. In her original statement Johnson claimed, among other things, that the check was given to her by an individual nicknamed Shorty, that together with this individual she attempted to cash the check at several banks, that she endorsed the check so it might be cashed by Shorty, that she did not know the check had been cashed, and that she did not receive any proceeds. All of these statements were false. In her appearance before the grand jury, Johnson testified that she first saw the check when someone brought it to her on the street, that she did not know how Shorty had obtained the check, and that she did not know where he lived. All of these statements were likewise false.
. Williams v. United States, 382 A.2d 1 (D.C.App.1978); Sheffeld v. United States, 397 A.2d 963 (D.C.App.1979); Reavis v. United States, 395 A.2d 75 (D.C.App.1978).
. The dissent suggests that absent perjury there is no affirmative duty on the prosecutor to correct false testimony, see dissenting opinion at n.l. But it makes no difference whether the testimony is technically perjurious or merely misleading. United States v. Barham, supra; United States v. Ramos Algarin, 584 F.2d 562 (1st Cir. 1978); United States v. Anderson, 574 F.2d 1347 (5th Cir. 1978); United States v. Sutton, 542 F.2d 1239 (4th Cir. 1976). Moreover, the judge at Johnson’s first sentencing hearing made it quite clear that her actual sentencing would be deferred, and she voiced her assent. Thus, her subsequent testimony that she had not yet been sentenced at a minimum “skirted the edge of perjury” (Boone v. Paderick, supra, 541 F.2d at 450), and prosecutorial correction was required.
. This standard is stricter than the usual harmless error rule. Kotteakos v. United States, 328 U.S. 750, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946); United States v. Fowler, 197 U.S.App.D.C. 208, 218, 608 F.2d 2, 12 (1979). A different and lesser standard is applied where other types of Brady violations are involved. See the discussion in Agurs, 427 U.S. at 104-07, 96 S.Ct. at 2397-2399.
. See note 1 supra. Except for its last sentence the confession is generally consistent with appellant’s trial testimony. There is a dispute whether appellant read and adopted the page on which the last sentence appears.
. As the Court there said (348 U.S. at 155, 75 S.Ct. at 198),
An admission which assumes this importance in the presentation of the prosecutor’s case should not go uncorroborated, and this is true whether we consider the statement an admission of one of the formal ‘elements’ of the crime or of a fact subsidiary to the proof of these ‘elements.’ It is the practical relation of the statement to the Government’s case which is crucial, not its theoretical relation to the definition of the case.
. For example, Johnson testified that she and appellant decided to give the teller a gratuity and that $25 or $30 actually changed hands. The teller denied this claim. This inconsistency formed only part of the ample grounds for impeaching the credibility of Johnson. See note 16 supra; transcript at 130-43. The fact that the jury may have had a variety of reasons *806for questioning Johnson’s critical testimony does not mitigate, and may magnify, the importance of her uncorrected lie about her sentencing status. See Napue v. Illinois, 360 U.S. 264, 270, 79 S.Ct. 1173, 1177, 3 L.Ed.2d 1217 (1959). In any event, there is as much reason as not to believe that Johnson’s perjury foreclosed a line of cross-examination which could have had a determinative impact on the jury’s decision.