Attorneys for convicted sniper John Allen Muhammad are asking that Fairfax County Commonwealth's Attorney Robert F. Horan Jr. and his office be barred from trying Muhammad this fall.

In pretrial motions filed in Fairfax Circuit Court, Muhammad's attorneys are renewing their argument that prosecutors in last fall's sniper trails used conflicting theories for the same crime.

A Virginia Beach jury convicted Muhammad, 43, in November of multiple murder and committing terrorism in the sniper shootings, with the Prince William shooting of Dean H. Meyers as the linchpin of the case. He was sentenced to death on both charges.

Fairfax prosecutors indicted Muhammad on the same charges shortly after his October 2002 arrest in the sniper shootings that left 10 dead in the Washington region, and Horan has said he will not bypass the case because another conviction exists. In Fairfax, Muhammad is charged with the killing of FBI analyst Linda Franklin outside the Seven Corners Home Depot.

While Muhammad was on trial last year for Meyers's killing, Horan was prosecuting co-conspirator Lee Boyd Malvo for Franklin's killing. Prosecutors alleged that Muhammad was the mastermind of the sniper rampage and that Malvo was the one who actually fired the weapon, based on Malvo's confessions. A Chesapeake, Va., jury convicted Malvo and sentenced him to life in prison without parole.

Muhammad's attorneys argue that the prosecutions conflicted because Horan claimed that Malvo "was a willful free agent" and that Malvo "did not act under the direction or order of Muhammad."

The defense would summon Horan to testify about his comments about Malvo, the attorneys wrote, and since Horan "cannot be both a witness and an advocate . . . he must be recused. Because he is in effect his office, the entire office is barred from participating."

Horan did not return a phone call yesterday seeking comment. The attorneys' brief does not quote Horan saying that Malvo was not directed by Muhammad; in fact, it notes that Horan said of Muhammad, "Maybe it was his plan. Maybe it was his idea." Instead, the attorneys cite a prosecution psychologist who said Malvo told him "he was a very, very willful individual . . . he was not an impressionable person."

The recusal request came in the first sheaf of pretrial motions filed Thursday by Muhammad's court-appointed attorneys.

Defense attorneys Peter D. Greenspun, Jonathan Shapiro and Christie A. Leary made a conditional request to move the trial out of Fairfax. They said they might rescind the motion if research shows it is unnecessary.

Fairfax County Circuit Court Judge Jonathan C. Thacher has scheduled Muhammad's trial for Oct. 4 and gave Muhammad's attorneys a deadline of this week to indicate whether they would request the trial be moved out of Fairfax.

A footnote in the papers states that the motion was filed because of Thacher's deadline but that the defense was seeking a jury consultant and rulings on other pretrial issues. "The decision to change venue cannot be finalized until these issues are resolved," the attorneys wrote.

Muhammad's attorneys asked Thacher to appoint a jury consultant, Jeffrey T. Frederick, to help them determine "where, if at all, can an untainted and non-biased" jury pool be found. An affidavit written by Frederick a year ago was submitted in support. Prince William County Circuit Court Judge LeRoy F. Millette Jr. rejected that request.

The defense in several motions raised the issue of the publicity surrounding the sniper case and how it would affect Muhammad's right to a fair trial. One argument asks Thacher to dismiss the terrorism charge because all citizens of Fairfax were victims of the alleged terrorism, and therefore "it is a legal impossibility to empanel an unbiased jury."

Thacher also had ordered Muhammad's attorneys to file their motions by Monday, despite Greenspun's plea that their appeal of Muhammad's first conviction also was due that day.

The defense filed the motions at 4 p.m. Thursday, and both Fairfax officials and the defense declined to release them publicly until yesterday.

Deputy Commonwealth's Attorney Raymond F. Morrogh sent a letter to Thacher on Thursday saying that prosecutors had received nothing and would not have enough time to reply by next Thursday, when the motions are scheduled to be argued.

The judge did not issue a ruling yesterday.