Lawyers for sniper John Allen Muhammad said yesterday they have written proof that their client's right to a speedy trial in Fairfax County was violated. Prosecutors immediately produced their own document and demanded a hearing.

At issue is the date of Muhammad's formal "arrest" on capital murder charges in Fairfax -- part of numerous charges filed against Muhammad in the October 2002 Washington area sniper slayings. Under Virginia law, a jailed defendant must be tried within five months of being arrested.

Lawyers in the case have written 10 briefs on the subject. Fairfax Circuit Court Judge Jonathan C. Thacher, who is considering the issue, said last week that he would decide soon whether the capital murder charges in Fairfax should be dismissed.

Muhammad, 43, and Lee Boyd Malvo, 19, were arrested Oct. 24, 2002. Within days, authorities in Virginia, Maryland and the District filed murder charges against the pair. Muhammad was shipped to Prince William County on Nov. 7, 2002, for his first prosecution; Malvo went to Fairfax.

Muhammad's attorneys noted that he was indicted in Fairfax on Nov. 6, 2002, and was available for proceedings there once he was jailed in Virginia. The defense argues that Muhammad's five-month speedy trial clock began ticking as soon as Fairfax sent a "detainer" notice to Prince William. The lawyers cited a 1993 Virginia appeals court ruling that a detainer sent from one county to another effectively served as an arrest.

The defense documents filed Friday and released yesterday show that Fairfax police did not fax a copy of Muhammad's indictment and bench warrant to Prince William until Jan. 6 of this year, after Muhammad had been convicted and sentenced to death in the Prince William case.

The jail's records show that a teletype was also received from Fairfax on that date seeking to detain Muhammad.

Muhammad was not brought before Thacher until June 22, more than five months after the fax was sent from Fairfax. Defense lawyers Peter D. Greenspun and Jonathan Shapiro believe that, regardless of when the detainer was served, Muhammad entered Virginia custody in November 2002 and had the right to begin his Fairfax proceedings then.

Fairfax Commonwealth's Attorney Robert F. Horan Jr. said last week that the detainer sent by police was merely a request to be notified if Muhammad were to be released, not a formal arrest. He also said that officers in the Prince William jail are not sworn deputies and do not have the power to serve warrants.

Greenspun mocked that logic in one brief, saying it turned the detainer into a mere request for a phone call from Muhammad's jailers asking: "We have this detainer. Do you really want him on this bench warrant for capital murder or should we just let him go?"

Greenspun also said in a brief that the acting superintendent of the Prince William jail, Maj. Charles Land, told him that his jail officers do have full arrest powers.

Deputy Commonwealth's Attorney Raymond F. Morrogh maintained in a response brief that the jailers cannot serve arrest warrants. He said Fairfax did not formally arrest Muhammad until May of this year, when Muhammad was served while on death row in Sussex, Va. Morrogh asked Thacher to hold a hearing on the issue Sept. 22.

Late yesterday, Morrogh filed another jail document showing that "the jail was instructed not to serve a detainer from Fairfax on the defendant."