Kennedy cousin Michael Skakel will provide a formal alibi for his whereabouts on the night that 15-year-old neighbor Martha Moxley was killed, his lawyer said Wednesday.

Skakel will offer the alibi within 20 days, defense lawyer Michael Sherman said during a motions hearing.

David Grudberg, another defense attorney, told Stamford Superior Judge John F. Kavanewsky Jr. that a murder case against Skakel should be thrown out because there was a five-year statute of limitations in effect at the time of the killing.

Prosecutors have contended that murder prosecutions are not subject to any statute of limitations. State law was changed in 1976 to eliminate time limits for prosecuting serious felonies, including murder.

The judge said he would rule later on the issue.

Skakel, a nephew of the late Sen. Robert F. Kennedy, was charged in January 2000 with the slaying of Moxley, who was bludgeoned with a golf club that matched a set owned by the Skakel family. Skakel was also 15 at the time.

He has pleaded innocent and remains free on $500,000 bail.

Kavanewsky had earlier rejected a motion from Sherman to force the prosecution to narrow its estimate of the time Moxley was killed. State's Attorney Jonathan Benedict said forensics experts cannot be any more specific than some time between 9:30 p.m. on Oct. 30, 1975, and 5 a.m. the following day.

The judge also rejected Sherman's request for the psychiatric or psychological records of prosecution witnesses, including students from the Elan School, a treatment center Skakel attended as a teen-ager. He said specific requests could be discussed during the trial.

Additionally, Kavanewsky turned down a motion to give the defense copies of video and audio tapes made during the polygraph test of Ken Littleton, a live-in tutor for Skakel and his elder brother who started the job the day Moxley was killed.

Prosecutors agreed to give Sherman a list of the witnesses they plan to call from the Elan School. Some former students at the school have testified that Skakel confessed to Moxley's killing, while others have said Skakel never confessed.

No trial date has been set.