The day Clark was scheduled to appear in court, John and a friend stood outside the house when they heard a gunshot. His father had killed himself, leaving his funeral clothes laid out on the bed along with two notes and $400 for John.
"Be a good boy, I love you," he wrote to his son.
John briefly moved in with his maternal grandparents, then stayed with friends and returned briefly to the family home. Soon he ventured on a cross-country trip, working odd jobs at a gas stations and factories, and eventually in construction in the Southwest.
"I had to learn about life when I got on my own, away from my family," he said.
John had brushes with the law, including 10 days in jail for stealing cars. He joined the Navy, but was discharged 182 days later. The young man — with no education and scars from a violent past — eventually settled in a nondescript Ohio farming town, now hit hard by a slowed economy.
He married and had a daughter even though, like his father, he didn't want children. "I was afraid to have kids because of my upbringing," he said.
After his 17-year marriage ended, he said his own daughter turned to crack-cocaine for solace.
In recent years, John, a diabetic without health insurance, also survived a heart attack. His daughter, now 25, lives nearby, but he said she has her own emotional problems, and he doesn't see much of his two young grandchildren.
After a recent arrest for drunken driving — his second — John has lost his driver's license and bicycles to house painting jobs, when the weather and sporadic construction projects permit.
"I've been able to block out my past," he said, sipping a brandy and ginger ale in his cramped but neat townhouse.
"When you are a kid, you try to trust my parents," he said. "I think I trusted the wrong people."
Today, Genie is well looked-after in an private adult home for the mentally disabled in Southern California. She can speak only a few words, but she has remembered the sign language that she was taught during the brief, federally funded research project that was eventually deemed a scientific failure.
John pulled out a stack of family photographs shuffled together in a plastic box — the only remnants from his past. "I tried to put [Genie] out of my mind because of the shame," he said. "But I'm glad she got some help."
Amid his work boots, painter's ladder and tools, the Bible sat on a small bookshelf next to a Boy Scout handbook and "Success for Dummies."
Only once did John's sparkling blue eyes moisten when he reflected on how his parents failed him.
"They didn't give me the tools, the knowledge about accomplishment and setting goals and the Bible and God," he said. "I feel at times God failed me. Maybe I failed him. But it's never too late."
Chris Francescani and Gerard Middleton contributed to this report.