David Kaczynski -- who heads an anti-death penalty group in New York -- told ABC News the Virginia Tech shooting "triggered a lot of dark memories" for him and his mother. Cho, a Virginia Tech student, gunned down 32 people before shooting himself -- while Ted Kaczynski carried out an 18-year bombing campaign that left three people dead and 23 injured.
"You are so full of questions," David Kaczynski said. "We didn't know Ted was violent, and we felt the same isolation as the Cho family. It's hard to disassociate yourself from your family member."
Cho's parents and sister have been in seclusion since the killings. In the family's only public statement, the sister released a written apology through a lawyer on behalf of the family five days after the shootings.
Katherine Moon, an associate at the Asia Society and a Korean-American, told ABC Korean immigrant culture -- which holds parents responsible for their children's triumphs and failures -- increases the Chos' isolation.
"Their son has, in effect, killed them too," she said. "The Cho family has been destroyed -- obliterated by their own son. You don't recover from this."