MEMORANDUM**

Vernon Delmar Mahan was convicted of armed bank robbery, 18 U.S.C. Sec. 2113(a) & (d) (1982 & Supp. IV 1986), and we affirmed on direct appeal. United States v. Mahan, No. 84-1370 (9th Cir. Nov. 26, 1985) (mem.). Mahan then filed a motion to vacate, set aside, or correct his sentence pursuant to 28 U.S.C. Sec. 2255 (1982), along with a request for an evidentiary hearing. His motion and request were denied. United States v. Mahan, No. CV-F-88-013 REC-P (E.D.Cal. Jan. 29, 1988). We review de novo, Campbell v. Kincheloe, 829 F.2d 1453, 1457 (9th Cir.1987), cert. denied, 109 S.Ct. 380 (1988), and affirm.

Mahan raises four groups of claims on appeal: (1) the prosecution failed to disclose exculpatory evidence and presented false testimony at trial; (2) the district court erred at trial in admitting an unreliable in-court identification of Mahan; (3) the district court erred at trial in reading the jury a general witness instruction rather than Mahan's proffered accomplice instruction; and (4) the district court erred in its treatment of Mahan's section 2255 motion. We consider each in turn.

1. Mahan claims three instances of prosecutorial misconduct: The prosecution allegedly (a) failed to disclose that police officers had promised a reduced sentence to accomplice Wayne Pennington in exchange for his testimony against Mahan and had threatened to arrest members of Pennington's family if he did not so testify; (b) knowingly presented false testimony by permitting Pennington to testify that no such bargain had been struck; and (c) failed to disclose that Pennington had denied his involvement in the bank robbery before confessing. Mahan raised only the first of these claims in his section 2255 petition.

a. A new trial is required where (1) the government fails to disclose evidence the defense might have used to impeach a government witness, and (2) there is a reasonable probability that, had the evidence been disclosed, the result of the proceeding would have been different. United States v. Bagley, 473 U.S. 667, 682 (1985); Brady v. Maryland, 373 U.S. 83, 87 (1963). Even if the prosecution withheld evidence relating to Pennington's motives for testifying, a review of the record indicates that the second of these requirements is not satisfied, because the evidence alleged to have been suppressed was in fact the subject of testimony before the jury. On cross-examination, Pennington testified that he hoped to receive a reduced sentence in return for his testimony, and that a police officer had threatened to arrest Pennington's family members if he did not implicate Mahan.

Where a government witness's possible motives for testifying are adequately explored before the jury, the prosecution's failure to disclose evidence relating to the witness's motives does not violate the defendant's due process rights. See United States v. Traylor, 656 F.2d 1326, 1335 (9th Cir.1981). Because defense counsel effectively used the allegedly undisclosed information to impeach Pennington, nondisclosure by the prosecution does not constitute a Brady violation. United States v. Browne, 829 F.2d 760, 765-66 (9th Cir.1987), cert. denied, 108 S.Ct. 1298 (1988).

The Jencks Act, 18 U.S.C. Sec. 3500 (1982), provides an independent basis for the disclosure of evidence. United States v. Bernard, 607 F.2d 1257, 1263 (9th Cir.1979). The Act requires the United States to disclose, at the defendant's request, prior statements of a government witness after the witness has testified. 18 U.S.C. Sec. 3500(b) (1982). For the reasons discussed above, any Jencks Act violation would have been harmless. See United States v. Phillips, 482 F.2d 1355, 1357 (9th Cir.1973) (per curiam), cert. denied, 419 U.S. 847 (1974).

b. Mahan's two other claims of prosecutorial misconduct were not presented to the district court in Mahan's section 2255 petition, so we decline to review them. Baumann v. United States, 692 F.2d 565, 573 (9th Cir.1982). Res judicata will not bar Mahan from raising them in a second section 2255 petition. See United States v. Donn, 661 F.2d 820, 823 (9th Cir.1982) (per curiam).

2. Mahan contends that the district court erred at trial in admitting Patricia Roe's identification of Mahan. We considered and rejected this claim on direct appeal. United States v. Mahan, No. 84-1370, at 3 (9th Cir. Nov. 26, 1985) (mem.). Mahan cannot raise it again in a section 2255 proceeding, absent unusual circumstances not present here. Feldman v. Henman, 815 F.2d 1318, 1323 (9th Cir.1987); Jack v. United States, 435 F.2d 317, 319 (9th Cir.1970), cert. denied, 402 U.S. 933 (1971).

3. Mahan's claim that the district court erred in reading the jury a general witness instruction was not presented to the district court in Mahan's section 2255 petition, so we decline to address it. As with his unpreserved claims of prosecutorial misconduct, Mahan will not be barred by res judicata from raising this claim in a second section 2255 petition.

4. Mahan contends that the district court committed three errors in its treatment of his petition: The district court failed to (a) permit Mahan to amend the petition before dismissing it; (b) refer the petition to a magistrate for an evidentiary hearing; and (c) refer the petition to the United States Attorney for a response. All three of Mahan's allegations are without merit.

a. Mahan never moved the district court for permission to amend his petition. The district court accordingly did not err in not permitting him to do so. In any event, the amendments Mahan proposes include only the claims he has raised for the first time on appeal; as noted above, res judicata will not bar his raising these claims in a second petition.

b. The district court did not err in refusing to refer Mahan's petition to a magistrate for an evidentiary hearing. Such a hearing is necessary only where a petitioner alleges facts which, if true, would entitle him to relief. Lincoln v. Sunn, 807 F.2d 805, 808 (9th Cir.1987). After carefully reviewing the record, the district court correctly determined that Mahan could not prevail on his Brady claim even if Mahan's allegation of intentional nondisclosure were true. The district court was thus correct in dismissing the claim without a hearing. See Nevius v. Sumner, 852 F.2d 463, 469 (9th Cir.1988).

c. The district court likewise did not err in denying Mahan's petition without ordering a response from the United States Attorney. Where "the files and records of the case conclusively show that the prisoner is entitled to no relief," a district court may deny a habeas corpus petition without briefing from the government. 28 U.S.C. Sec. 2255 (1982).

AFFIRMED.