In 1961, at age thirty-three, David started demonstrating his psychotic tendencies when he attacked a woman with a hammer. After a stint in jail, a prison break, and another stint in jail, he came out a reformed man. In 1978 he relocated to San Francisco to work in a print shop. By August 1979 he was back to his old tricks. He started killing mostly women in hiking trails in Tamalpais State Park in San Francisco. He cruelly shot and stabbed his victims as they knelt and pled for their lives. By the end of 1980, after six murders by the "Trailside Killer," authorities linked him with the Zodiac Killer. By 1981 he had moved his hunting grounds to trails as far away as Santa Cruz. In May 1, 1981, police went to the print shop to investigate the whereabouts of Heather Scaggs, his ninth victim, who disappeared after he gave her a ride home from work. There they recognized him from the "Trailside Killer" police sketches and arrested him. Evidence linked him to the some of the murder weapons and the murder of another woman who he knew.