MANASSAS, Va. - To get the death penalty for sniper suspect John Allen Muhammad, prosecutors must show he killed more than one person over a three-year period - or else rely on the state's new terrorism act, which has yet to pass judicial review.

If they choose the first alternative, prosecutors will have to specify which of the multiple killings Muhammad is accused of they intend to present at his trial if they want defense lawyers to turn over alibi evidence for them, Judge LeRoy F. Millette Jr. ruled yesterday.

That means prosecutors must present a broader case than simply the facts surrounding the Oct. 9 shooting of a Gaithersburg engineer, Dean H. Meyers, 53, outside a Manassas gas station.

The prosecutors, who have given more than 2,000 pieces of evidence to the defense, said their request for information on Muhammad's whereabouts at the time of the killings is not too much to ask from the defense team, but the defense attorneys were reluctant to turn over information that might not come up at trial.

Because Virginia's terrorism statute has never been reviewed by a court, prosecutors would be on surer footing if they use the multiple murders justification for capital punishment.

In a bill of particulars filed in May, prosecutors listed 11 killings in addition to that of Meyers in which they say Muhammad may have been a principal in the first or second degree.

Prosecutors, in turn, asked the defense attorneys to let them know whether they intend to produce alibi evidence for those 11 killings. Defense lawyers responded that they must present alibi evidence only for the killing of Meyers, for which Muhammad, 42, is facing trial first.

"The commonwealth will not take the position that they are bound to prove every shooting they have listed," said defense attorney Peter D. Greenspun in court yesterday. "They're using this as a broad-based discovery device."

Millette attempted to strike a compromise, ruling that if prosecutors want to see alibi evidence, they must specify which of the 11 additional killings they intend to present at trial. Defense lawyers will then have 24 hours to respond.

Last month, the defense team filed a response about alibi evidence for the Meyers' killing, but it was sealed by the judge.

The trial is set to begin Oct. 14 in Virginia Beach, where it was moved to better the odds of finding an impartial jury not subjected to pre-trial publicity. The trial of 18-year-old Lee Boyd Malvo, who is alleged to be a co-conspirator, is set to begin Nov. 10 in Chesapeake.

The two are linked to killings in Alabama, Louisiana, Maryland, Virginia and the District of Columbia.

Also yesterday, the Prince William Board of County Supervisors voted to set aside $1 million to pay for investigative and trial costs in the Muhammad case. The U.S. Justice Department plans to contribute $200,000.

The logistics of moving the trial 200 miles to the south are daunting. Millette and the lawyers in the case dealt with some of those issues yesterday. They agreed that the trial will be broadcast on closed-circuit television in two remote locations, one for the news media and one for families of the sniper victims.

Millette said the courtroom in which the trial is to be held has just 43 seats.

Several will be set aside for the lawyers' staffs, leaving the balance to be split between the news media and the public. Millette said he plans to run the trial five days a week instead of the usual four. The trial is expected to last from four to six weeks.

Millette asked Greenspun, the defense attorney, whether he needed any additional seats in the courtroom besides those for his staff.

"I heard something about my mother needing a seat," Greenspun said with a straight face.

The judge laughed and said, "We'll have to rotate the mothers in and out."