MEDFIELD, Mass. (AP) _ An ex-Marine whose court-martial case was the true story behind the movie ''A Few Good Men'' was found shot to death three months after he disappeared.

David V. Cox, 27, was reported missing by his girlfriend on Jan. 4. He left behind an uncashed paycheck and the keys to his truck.

His decomposed corpse was found Saturday about a mile from the nearest road, after a canoeist spotted a white sneaker on a remote riverbank.

Cox had been shot once in the back of the neck and three times in the torso, Norfolk County District Attorney William Delahunt said.

''A Few Good Men,'' starring Jack Nicholson, Tom Cruise and Demi Moore, was based on an attack in which Cox and several other Marines were accused of beating another Marine to death.

Seven Marines accepted plea bargains, but Cox and two others opted for courts-martial. Cox was acquitted and later received an honorable discharge.

Cox had considered suing filmmaking company Castle Rock Entertainment, his lawyer, Neil Kane, said shortly after he disappeared.

Police had no suspects. Delahunt said the motive also was unknown, but he didn't think the film had any connection to Cox's death.