When he was 7, his brother died of leukemia. By the time he was 9, he had started using alcohol and drugs. He ran away from home at 11 and was picked up by a man who raped him and kept him for several days. He eventually escaped, with the help of his grandfather, who began to sexually abuse him. That continued for several years.
He first came to the attention of authorities when he was 15, when he was arrested for burglary. By the time he was 19 he had fathered a daughter, and he married and divorced her mother twice. He was repeatedly jailed for public intoxication.
His mother died when he turned 24, and that turned out to be a really bad year. He was convicted that year, at the young age of 24, of murder and sexual mutilation.
"He later confessed to three prior sexual mutilation killings," Van Soest says.
"When you look back at a story like that it's almost completely predictable as to what's going to happen," she adds. "Even the nature of the crimes had some direct connections to what happened to him in childhood."
But the critical question remains. Could that story have had a different ending if someone had come to Greg's aid while he was still a child? Or was he on an irreversible course?
"I don't believe so," Van Soest says. Greg tried for two years to get through the ninth grade, she adds. He went to school regularly, worked hard, and got fair grades, but troubles at home just overwhelmed him.
"There was a determined kid in there," she says. "If somebody had noticed, and if somebody had intervened, I believe he was salvageable," she says.
Nobody really knows for sure, of course. Maybe some questions have no answers.
But this study suggests my dad was right. We need to pay a lot more attention to those twigs.
Lee Dye’s column appears weekly on ABCNEWS.com. A former science writer for the Los Angeles Times, he now lives in Juneau, Alaska.