Ever since he graduated from high school in Sacramento, Calif. in 1972, 21-year-old Gary Martin Acker has suffered through a series of depressing false starts. Last week he was on trial for his life, accused of fighting as a pro-Western mercenary during the recent civil war in Angola. Acker was one of 13 defendants, including two Americans, who faced possible death sentences at the hands of Angola's new Marxist government.

For Acker, a moody ex-Marine with a history of crumbled ambitions, the prospect of execution by firing squad was both ironic and pathetic. He had never been in combat before he was shot in the leg and captured within five days of his arrival in Angola last February. Six other soldiers in his patrol were killed. Back home, Acker's mother, Joyce, claims her son was worried about Communism. But Acker has denied that his motives were ideological. "I did not come here for the money; I did not come to fight Communism," he told a crowded courtroom in Luanda, Angola's capital. "I came here because of problems with my family and myself."

Acker's parents, who borrowed $5,000 to send two American defense lawyers to the trial, describe their son as a loner who liked guns but not girls. The walls of his room are covered with posters against drugs, drinking and smoking. He enjoys movies about combat and saw The Godfather three times. "He's a hard person to understand," says his mother. "He pretends to be tough as nails, but underneath he's not." Gary joined the Marines fresh out of McClatchy High School. "He really wanted to go over to Vietnam and fight," Joyce Acker recalls. "He was disappointed when the fighting ended, but I was glad." Acker spent six months on the aircraft carrier Ranger, then returned to the U.S. after he was chosen to fill a prized opening at the Naval Academy Preparatory School in Bainbridge, Md.

He dropped out after three months—"Gary gets discouraged very easy," says his mother—and was shipped off to Camp Lejeune, N.C. There, explains one of his lawyers, Acker was given a general discharge from the Marines "because he hinted he might harm a lieutenant he thought was harassing him." (On trial in Luanda, Acker said he had set aside a bullet to kill his Marine platoon leader.)

Acker lived with his parents for a while, then bought a 10-speed bike and headed for Europe. Pedaling around Holland and Germany, he was delighted by a new sense of freedom. "The whole experience gave him a different outlook," says his father, Carl, a fireman. "The point he kept bringing up was that you could leave your bike or your wallet some place and nobody would touch it."

Though Acker had planned to spend three or four months overseas, his trip lasted only six weeks. "Gary is the type who can only be away so long," observes Mrs. Acker. "He gets kind of homesick." Back in Sacramento, he took a job with a manufacturer of rain gutters, but quit after one day because the company docked employees for gutters they damaged during installation. "He destroyed more than he got together," says his mother. "I guess he lost money on the deal."

Though Gary rarely talked politics with his family, Mrs. Acker believes he first became interested in Angola after reading a newspaper story last Christmas about a recruiter of mercenaries. About a month later he told his parents he was heading for New York. Then, in early March, the State Department phoned with the news: Gary was missing in action. A month later he was reported held prisoner. For the bewildered Ackers, it was but another mystery involving the enigma that is their son.