SAN CLEMENTE, Calif. -- U.S. Marine Corps officials Friday identified a Marine found shot to death Thursday.

Private First Class Stephen C. Serrano, 20, an El Dorado, Calif., native, was a field radio operator serving with the 2nd Battallion of the 5th Marine Regiment at Camp Pendleton, according to a Marine news release.

He joined the Marine Corps March 11, 2007, and had not deployed in support of Operation Iraqi Freedom or other operations, a U.S. Marine spokesman said.

His body was found lying in a fetal position Thursday in brush off a winding road in San Clemente. Serrano suffered a gunshot wound to his upper body, authorities said.

A hiker following a trail in the 1000 block of Calle Cordillera discovered the body about 9 a.m., said Jim Amormino of the Orange County Sheriff's Department.

The man had been dressed in sand-color military fatigues commonly worn by Marines, Amormino said.

Authorities do not know if the man was killed where he was found or his body was dumped there. Investigators from the U.S. Navy and the Marine Corps have joined the probe.

The body may have been there for about a day, Amormino said.