Like Papenfuss, Hanlon said his hope for the collaboration with Odle was to understand the "behaviors, dynamics and relationships" to help identify potential family mass murders and to intervene.
Both suggest the biggest factor in the shaping of a potential family killer is a history of childhood abuse.
"It's hard not to overstress that," Hanlon said. "It doesn't matter how long or how much time has passed, those experiences are rarely ever forgotten or forgiven and stay with people and influence their character and their choices in relationships.
"Often a precipitating event occurs even when that deck is stacked with factors -- a sudden loss that occurs in a person's life, something has been taken away from them," he said. "In this case, in his view his parents were abandoning him and ejecting him from the home and it came on the heels of his girlfriend basically rejecting him."
Police found the massacre when Odle's father didn't show up for shift work. They immediately did a search for Odle, who was staying at a local hotel. He never denied murdering his family.
But what disturbed Hanlon most about Odle's story was the parental abuse.
"She and her husband had managed to conceal that abuse quite effectively for many years and it wasn't exposed," he said. "Certainly, if people had been more aware and knew what to look for and intervened, they probably would be alive today."