Stayner would later tell both the FBI and a San Jose TV reporter that he had his first violent fantasy about women when he was seven years old: On a shopping trip with his mother, he envisioned opening fire on the supermarket cashiers, slaughtering them en masse. His cousin Ronnie Jones, a camping companion and perhaps his closest friend, recalled how Stayner would often doodle pictures of naked girls in a notepad. The two frequented the Merced River together, but when Ronnie would run down to skinny dip with the girls, Cary refused to join him. He apparently dated several women for short periods of time, but he seemed incapable of establishing any lasting relationship.

By his midtwenties, Stayner had settled into a job repairing windows for Merced Glass and Mirror, sharing a house with Jerry Stayner, his father's brother, a truck dispatcher for a hay company. In 1989 Steven—who friends say never really put his life back together after his ordeal, though he got married and fathered two children—was killed in a motorcycle crash. Cary, like the rest of the family, was said to have been devastated. Then, in 1990, police discovered Jerry Stayner sprawled dead in the bedroom of the house where he lived with Cary, with a shotgun wound to the chest. Cary was questioned about the killing, but he had an alibi—he said he had been at work when the shooting took place—and was not considered a suspect, says a Merced detective who worked on the case. Police focused their investigation on an unknown vagrant whom Cary claimed was lurking around the house shortly before the killing. But the vagrant was never found, and the murder went unsolved.

Stayner seems to have maintained a quiet, unexceptional existence for the next several years. Then, one day in 1996, a coworker went out into the yard of Merced Glass and Mirror to find Stayner slamming his fist against a piece of wood and bleeding from cuts on his hand. "He said he felt like he was having a breakdown and said he was all nervous and didn't know why," the colleague later told the San Francisco Chronicle. "He said he felt like getting in his truck, driving into the office, and killing everyone in there and torching the place." Stayner's boss drove him to a Merced psychiatric center, where he spoke with a therapist. Stayner never went back to his job again. He told former coworkers that he was thinking of moving to Santa Cruz to pursue a cartooning career.

Instead he headed east, to the Sierra, back to the woods. By then his father had lost his job at a Merced tomato cannery and had moved with Kay into a trailer park in the town of Atwater, where two of Stayner's three sisters also lived. Stayner appears to have told few people outside of his immediate family where he was going. In El Portal, just west of Yosemite National Park, he found a job as a handyman at the Cedar Lodge, a sprawling complex of rustic pine bungalows that straddle the Merced River. He rented a room above the Cedar Lodge Restaurant & Lounge, a 1950s-themed diner with red Naugahyde banquettes and a vintage jukebox, and did odd jobs around the motel. He was "a cool guy" who mixed easily with the rest of the staff, according to a waitress at the diner. "At night we'd all hang out, watch a video in somebody's room. He was totally likable. He was ordinary."