Joseph Proctor told his girlfriend he was popping out to the convenience store in the quiet Mexican beach town where the couple had just moved, intending to start a new life. The next morning, the 32-year-old New York native was dead inside his crashed van on a road outside Acapulco. It is at least the third case this year in which soldiers, locked in a prohibitionist drug war with trafficking organizations, have been accused of killing innocent civilians and faking evidence in cover-ups. Such scandals are driving calls for civilian investigators to take over cases that are almost exclusively handled by military prosecutors and judges who rarely convict one of their own.