A senior Justice Department official said prosecutors would bring federal charges in Maryland, where the string of 13 attacks began and ended, and where six of the 10 who were slain died.
The federal government's move comes as local prosecutors continue staking claims to the case and as investigators from Washington, D.C., to Washington state explore links to other unsolved crimes.
At a news conference last night in Tacoma, Wash., authorities said ballistics tests have linked the two suspects in the Washington-area sniper attacks to a February slaying there and to a shooting at a synagogue.
Tacoma Police Chief David Brame said John Allen Muhammad and Lee Malvo Boyd had access to a .45-caliber semiautomatic handgun used to kill Keenya Cook.
The tests performed by the Washington State Crime Lab also linked a .44 Magnum handgun to the suspects in what police described as a "vandalism incident" in which two shots were fired into Temple Beth el in Tacoma between May 1 and May 4.
Earlier yesterday, officials in three Virginia counties charged Muhammad, 41, and Malvo, 17, in the sniper attacks.
They argued that Virginia was best positioned to try the men because, unlike Maryland or the federal court system, it allows capital punishment for offenders under 18.
Montgomery County State's Attorney Douglas F. Gansler beat the rush last week, filing the first murder charges.
That rankled Justice Department officials and spotlighted behind-the-scenes tensions between the ambitious county prosecutor and Maryland's U.S. attorney, Thomas M. DiBiagio.
Gansler said last night that he was unaware of the federal prosecutor's plans, but he called it a "disappointment for the people of Montgomery County."
"Reason and common sense would suggest that we should be the first to prosecute the case," Gansler said.
"But the federal government, they have different interests here that may not comport with the interests of people in Montgomery County."
DiBiagio did not return phone calls. His office has said it would not respond to media inquiries about the case.
A Justice Department official said the decision to file federal charges did not mean U.S. prosecutors would automatically hold the first trial: "[T]he fact is that no decision has been made about who's going to go first."
But the federal charges could present a more compelling case for Virginia to hold the first trials.
Although the two suspects would face different charges in state court than in federal court - murder, for instance, instead of extortion - Virginia's broad double jeopardy law prohibits a second prosecution based on the same set of facts.
Because the suspects are in federal custody, U.S. Attorney General John Ashcroft will determine which jurisdiction controls the case.