ALBANY, N.Y. (AP) _ Civil rights leader Medgar Evers' body was exhumed and secretly re-examined here as prosecutors prepare to try a white supremacist for the third time in his 1963 slaying, officials confirmed Wednesday.

Evers' body was exhumed Monday from Arlington National Cemetery in Virginia, said Maj. Arlene Beatty, a U.S. Army spokeswoman. She said Mississippi prosecutors, who last fall reopened the investigation into Evers' killing in that state, requested the exhumation.

The body was brought to Albany Medical Center, where Dr. Michael Baden, chief of forensic services for the state police, performed an autopsy, WTEN-TV in Albany reported.

The station said the prosecutors had requested the services of Baden, a pathologist for congressional committees that investigated the assassinations of President Kennedy and civil rights leader Martin Luther King Jr.

Baden on Wednesday night wouldn't deny that an autopsy on Evers was performed in Albany. He wouldn't elaborate, saying only, ''It's a homicide case investigation.''

Evers' body was reburied in Arlington early Wednesday, Beatty said.

It wasn't immediately known what evidence prosecutors may have sought from the autopsy, though they have said that a key piece of evidence for the third trial of Byron De La Beckwith is a rifle believed to be the murder weapon.

The top prosecutors in the case, Hinds County, Miss., District Attorney Ed Peters and Assistant District Attorney Bobby DeLaughter, didn't immediately return telephone messages left at their homes Wednesday night.

Evers, a field secretary with the National Association for the Advancement of Colored People, was shot to death June 12, 1963, by a sniper who ambushed him in the driveway of his Jackson, Miss., home.

The assassination focused national attention on the civil rights struggle in Mississippi and helped push forward civil rights reforms.

Beckwith, 70, was tried twice in 1964 in the slaying, but all-white juries deadlocked. Charges were dropped in 1969, and he moved to Signal Mountain, Tenn., eight years ago.

Last fall, Peters' office reopened the investigation into Evers' death amid charges of evidence- and jury-tampering, and a federal grand jury indicted Beckwith a third time.

Beckwith is an admitted white supremacist but has denied killing Evers, saying the charges were intended to ''incite the lower forms of life to force and violence against the country clubs.''

The Tennessee Court of Criminal Appeals on Monday ordered Beckwith extradited to Mississippi to stand trial again. Beckwith, who has been held in a Chattanooga, Tenn., jail since Dec. 30, has 30 days to appeal the ruling.

The murder weapon, a rifle found near where Evers was slain, had Beckwith's fingerprint on it, but he maintains the weapon was stolen from his home. The gun was a key piece of evidence in Beckwith's first two trials but had been missing since the second trial until the fall of 1989. The gun had been in the possession of the family of Hinds County Circuit Court Judge Russell D. Moore III, who died in 1989. Moore apparently got the gun after the case was closed in 1969.

In the renewed investigation, new witnesses stepped forward, including a former Ku Klux Klansman who later became a FBI informant and was quoted in 1975 book on the Klan as saying Beckwith told him he shot Evers. DeLaughter, the assistant district attorney, said other new witnesses corroborated that story.

Beckwith, an outspoken opponent of integration since 1954, ran unsuccessfully for lieutenant governor in 1967 after his trials in the Evers slaying. In 1973, he was convicted in Louisiana of possessing dynamite and served five years in prison.

Beckwith can be tried again without double jeopardy because no verdict was ever reached and no statue of limitations exists in murder cases.