KNOXVILLE (WATE) - Ted Kaczynski, the man known as the Unabomber, is currently serving a life sentence without parole at the Super Max facility in Florence, Colo.
He was responsible for bombings spanning three decades that left three people dead and nearly two dozen injured.
The terror came to an end after his brother David became suspicious that Kaczynski was behind the crimes and called authorities.
David Kaczynski now tours the country with a message about the impact of mental illness on families and society.
David says mental illness sent his brother's life on a terrible trajectory. That path caused tremendous pain for their family, but he never dreamed his brother would become an American terrorist.
He spent time at Volunteer Ministry Center in Knoxville Thursday prior to his speech for the organization's 25th anniversary dinner.
The dinner was held in memory of Don Sproles at the Crowne Plaza Hotel.
David says he sees parallels to his own family when it comes to the effects of mental illness.
He says turning his brother in 16 years ago is something he had to do.
"The time I realized it was definitely the right decision was when Ted was arrested, and they found, in addition to lots of incriminating evidence, a live bomb in his cabin under his bed," Kaczynski said. "(They were) apparently ready to be mailed to someone. I think at that point, we realized we did what we had to do."
Years before he became known as the Unabomber, Ted Kaczynski was David's smart, older brother. Ted was so smart he was accepted to Harvard at age 16.
David says Ted had always been different and in the end the family suffered for it.
"I think ultimately most people looking at their own families and thinking about themselves realize we were dealt a really tough situation and we handled it as best we could," David Kaczynski said.
It was the rambling, 35,000-word "Unabomber Manifesto," published in the newspapers across the country, that roused the suspicions David's wife, Linda.
David soon came to the realization that his brother could be the deranged mastermind behind the crimes. The family first analyzed the situation before making the decision to turn Ted into the authorities.
"We kind of got two questions, two huge questions. One, is he responsible and the other question is what do we do about it?" the brother recalls. "You know, on one hand, clearly there was an urgency to stop the violence. If we didn't act, somebody might pick up a bomb and get killed. On the other hand, there was the realization that, gee, if I hand my brother over, he could be executed."
The final decision came after considering one of the Kaczynski family's key members.
"I thought of the effect on Ted, but I also thought of the effect on our mother," he said.
Since Ted Kaczynki's arrest 16 years ago, David has had no contact with his brother.
"I continue to write to Ted, but unfortunately, there's never been a response," Kaczynski said. "It's kind of like knocking on a door that never opens, but I know he's in there somewhere."
Kaczynski says his brother's torture is both physical and mental. "I really see that he's in two prisons. One is the physical prison where he will spend the rest of his life. The other is maybe this more dire prison of mental illness."
David Kaczynski still holds out hope he will one day hear from his brother, who is now 70 years old.