SAN DIEGO -- An autopsy confirmed Friday that an unidentified man found dead in a dirt lot on Pala Indian Reservation was slain, a sheriff's official said Friday.

The body, which was discovered by a reservation security guard off the 34600 block of Lilac Road early Thursday afternoon, bore clear signs of suspicious trauma, Sgt. Roy Frank said.

The sergeant declined to specify the cause of death.

Investigators are hoping tips from the public will help them identify the victim, who was black, Hispanic or Native American and appeared to be between 18 and 25 years old.

It was unclear if the man was killed in the area, which often is used by locals as a place to ride dirt bikes and other off-road vehicles, or was dumped there after being slain elsewhere, Frank said.