The Fairfax County murder case against John Allen Muhammad formally ended yesterday when a judge rejected the prosecution's request to reconsider his ruling last week dismissing the case.

Muhammad's attorneys successfully argued that prosecutors had violated Muhammad's right to a speedy trial by issuing a "detainer" for him in January of this year in the Prince William County jail but not bringing him to trial in Fairfax until October. Virginia law requires that a jailed defendant be tried within five months of arrest unless the defense waives that right, and a 1993 appeals court decision ruled that a detainer, though not a legally defined process, carried the same weight as an arrest.

Fairfax Circuit Court Judge M. Langhorne Keith on Friday cited the 1993 ruling as precedent in issuing his order to dismiss all Fairfax charges against Muhammad. Fairfax prosecutors quickly filed a motion asking Keith to reconsider, but yesterday he declined.

Keith's ruling cannot be appealed. Virginia prosecutors may appeal only rulings on constitutional questions and suppressions of statements. And though the right to a speedy trial is found in the U.S. Constitution, Keith based his decision on Virginia law, which says that a jailed defendant who isn't tried within five months "shall be forever discharged from prosecution for such offense."

Fairfax Commonwealth's Attorney Robert F. Horan Jr. did not return a call yesterday seeking comment. He previously argued that a detainer was no more than a request for notification when a prisoner was to be released, and he noted that Fairfax specifically had instructed the Prince William jail not to arrest Muhammad.

Peter D. Greenspun, one of Muhammad's court-appointed attorneys, said the prosecution's arguments for reconsideration of the dismissal "were exactly the same as they previously made, so we hoped for and expected the exact same result."

Fairfax had charged Muhammad, 43, with the Oct. 14, 2002, slaying of FBI analyst Linda Franklin in Seven Corners. Co-defendant Lee Boyd Malvo was convicted of the same killing last fall and sentenced to life in prison.

The ruling does not affect charges in any other jurisdiction against Muhammad in the 10 sniper slayings committed in the Washington region in October 2002, or killings in Alabama and Louisiana committed in September 2002. It also does not affect Muhammad's first set of convictions, in Prince William, for which a jury last fall sentenced him to death. The appeal of that case, before the Virginia Supreme Court, is expected to be argued next month.

But the only other Virginia murder case pending against Muhammad may also be in jeopardy. Muhammad is accused in the Oct. 11, 2002, slaying of Kenneth H. Bridges in Spotsylvania County. Authorities there also filed a detainer for Muhammad in Prince William, meaning the same legal argument could be made for dismissal of the case. Greenspun said yesterday he did not know if he or Jonathan Shapiro, who both represented Muhammad in his first two trials, would be appointed in Spotsylvania.