SAN CLEMENTE – The Marine Corps on Friday identified the troop found shot to death near Camp Pendleton.

Pfc. Stephen C. Serrano, 20, of El Dorado, was found Thursday lying face down in a drainage ditch about 50 yards up a hillside. He had been shot in the chest.

Serrano was a field radio operator who joined the Marines in March last year, officials said.

The Orange County Sheriff's Department and the Naval Criminal Investigative Service are investigating his death and an autopsy had been planned for Friday.

Serrano probably was killed at the site but “robbery is definitely ruled out” as a motive, sheriff's spokesman Jim Amormino has said.

He was wearing desert fatigues and boots and his cap was found about 15 feet away, Amormino said.

Serrano lived at the nearby Marine base and was married, Amormino said. He was believed to have been in the ditch less than 24 hours.