SAN DIEGO -- A Camp Pendleton-based sailor found dead in a guard shack at the North County military base was shot multiple times, and someone apparently tried to cover up the slaying by setting a fire, authorities said Thursday.

A suspect in the killing of 29-year-old seaman August Provost of Houston, Texas, is in military custody. The detainee, whose name was being withheld, was linked to the crime through physical evidence and statements he made, said Capt. Matt Brown, director of public affairs for Navy Region Southwest.

Despite concerns aired by gay rights activists, however, investigators have found no evidence that Provost was murdered because of his sexual orientation, Brown said. The captain declined to disclose any other suspected motive for the slaying during a late-afternoon briefing.

According to media accounts, Provost was gay. Those assertions are supported by statements the sailor himself made on his MySpace page.

A fellow sailor arriving to relieve Provost on sentry detail found him dead at the entrance to an assault-boat compound on the western side of Camp Pendleton about 3:30 a.m. Tuesday. Provost had been on duty at the guard station for four hours, Brown said.

Two "persons of interest" were taken into custody and held for questioning. One has since been released, Brown said.

Despite the fact that the victim was shot, military officials have held off on specifying a cause of death, pending completion of further postmortem tests.

Ben Gomez, head of the San Diego chapter of American Veterans for Equal Rights, a national advocacy group for gay and lesbian military personnel, said Wednesday that he and other local activists suspected Provost's death was a hate crime. Gomez urged the military to conduct a thorough and open probe into that possibility.

Likewise, Reps. Susan Davis and Bob Filner of San Diego have called on the Pentagon to expeditiously investigate the prospect that Provost may have been killed because of his sexual orientation.

Gomez, citing unnamed sources with access to a report on the seaman's death, said there was evidence that Provost was slain during or after an argument with another sailor about the victim's homosexuality.

The Navy spokesman, however, told reporters Provost appeared to have been a "random" victim.

Brown would not confirm or deny reports that the victim's body had been burned, saying that determination also was on hold until all autopsy findings are complete.

No one heard gunfire in the area of the guard shack during the hours prior to the discovery of Provost's body, the captain said.

Per regulation, the seaman would have had a sidearm while serving sentry duty that night, Brown said. The spokesman declined to say if Provost's gun was found with his body.

Provost, who enlisted in the Navy in March 2008, was a member of Assault Craft Unit 5, whose personnel are assigned to duties involving hovercraft.

He was due to deploy overseas soon, according to Brown, who described the victim as "a rising star in the Navy."

His family said he enlisted to pay for college.