Phillippines ? An autopsy revealed that a Peace Corps volunteer found buried in a shallow grave in a Philippine mountain village was killed by blows to the head, officials said Saturday.

Julia Campbell, 40, of Fairfax, Va., suffered “multiple blunt traumatic injuries of the head,” police Chief Inspector Mamerto Bernabe, a pathologist who led the autopsy, told reporters at a suburban funeral parlor.

Crime laboratory head Chief Superintendent Arturo Cacdac said Campbell’s remains were immediately turned over to the Peace Corps after the autopsy, which was observed by U.S. forensic experts.

Police are looking for a man who may have been involved in Campbell’s death in the northern Philippines. Investigators said that a witness claimed he saw a man in the area of the shallow grave in Banaue township where Campbell’s body was found on Wednesday, 10 days after she went missing.