A Killer in the Family

Today the family of Seung-Hui Cho released a statement to The Associated Press saying they felt "hopeless, helpless, and lost" and would "do whatever we can to help authorities understand why these senseless acts happened."

Throughout the week, they have been the recipients of overwhelming criticism from observers who continue to wonder how this tragedy could have happened, how they missed the warning signs, and how could their child could commit such a horrible act.

One man, David Kaczynski, is far too familiar with the plight of the Cho family.

His brother Ted Kaczynski is known to many as the Unabomber, the brilliant mathematician who was also a calculating murderer. For a period of 17 years, beginning in the late 1970s, Kaczynski created homemade parcel bombs, killing three and injuring 23 people.

ABC's Martin Bashir met with David Kaczynski on Thursday at the Melanie Ilene Rieger 11th Annual Conference Against Violence in Waterbury, Conn.

Like Seung-hui Cho, the Virginia Tech student who killed 32 people on Monday, Ted Kaczynski also produced a manifesto -- a document that raged against society and, in particular, the effects of technology.

For Kaczynski's younger brother David, this week has been a dreadful experience of deja vu -- the horror and anguish that comes with finding out that a member of your family is a killer.

"This all brings back terrible memories," he said.

'What's Wrong With Teddy?'

David and his brother Ted grew up together in Chicago, their family the apparent model of a perfect picture. But behind the happy portrait there were worrying signs of the trouble to come.

"I loved my brother. I adored him. He was a good big brother and always treated me with kindness, sometimes incredible kindness," said David Kaczynski. "I think there was probably a time when I asked my mom, 'What's wrong with Teddy,' and she said, 'What do you mean, there's nothing wrong with your brother.'"

When David Kaczynski looked at his brother, he saw an isolated, sensitive individual who had problems socially. Ted, said his brother, didn't have "the kind of social interactions that I had. He was much more comfortable reading a book in his room than hanging out with his friends or playing sports."

Kaczynski's family searched for a way to amend his behavior.

"We talk about it endlessly. You have to remember that in Ted's case, unlike Cho, there had never been any violence or threats of violence. We had thought Ted was completely harmless," said Kaczynski. "My nightmare of Ted was that he might hurt himself, you know, because after a period of time it became clear that he was gripped by some kind of despair."

Troubled…and Turned Away

Ted Kaczynski had estranged himself from society and excluded himself from family events. Like Cho, Kaczynski's writings were also called into question and his behavior had began to worry those close to him.

"We actually ended up calling a family doctor in the area whom Ted had seen and hoped to persuade her to use her influence with Ted to persuade him to get into treatment," said Kaczynski, "but even then I thought we were clutching at straws."

Kaczynski admits that at first, his brother's odd behavior was accepted as part of his character. "That's the way Ted is. He isn't a label in a book, he's my brother. He isn't hurting anyone. He's living the life he's choosing."

He was also influenced by the stigma often attached to mental disabilities. "It's a shameful thing," he said. "If we could bring the whole mental illness out of the shadows and talk about it honestly, particularly in this day and age when there are effective treatments available, people like my brother, people like Mr. Cho, perhaps could get the treatment available."

Like Cho, Ted also came into contact with those who might have helped him -- a psychologist at Harvard and then at the University of Michigan.

"Ted had actually sought out mental treatment," said Kaczynski. "Once at the University of Michigan where he was a grad student and much later while he was living in that cabin in Montana. [In] the Montana instance, I think he actually had written to the country health office to see if he could do psychological counseling through the mail and he got a polite letter back saying that this was not possible…The end result was that this man who was very ill, needed some help [who] was essentially turned away."

'This Is One of Us'

Soon after the Oklahoma bombing in 1995, perpetrated by Timothy McVeigh, Ted Kaczynski sent his manifesto to two newspapers and demanded that they publish its contents. When they did so, the words seemed familiar to his brother David.

He contacted the FBI which led to his brother's arrest. Suddenly the family faced a terrible truth -- one of their own was a murderer.

"I think there is always a level of guilt," said Kaczynski. "I mean we, I had never done anything wrong. I had never done anything to hurt Ted, but some sense that this is one of us. How could one of us do this? There is an element of shame, there is an element of guilt, there is an element of worry and wonder…where did this come from?"

David is now the executive director of New Yorkers Against the Death Penalty. He told "Nightline" that he sees a lot of people affected by tragedy that have no reason to feel guilt but do feel it and look for some constructive positive response.

"If you can take some part of it," he said, "and turn it into some human connection, education, enlightenment, something that could make the world a better place that's kind of the only shred of hope that you have because so much hope has been taken from you."

Preventing 'the Next Ted Kaczynski'

Kaczynski is committed to stopping another tragedy like the one that tore his family apart. He was accompanied at the Conference Against Violence by one of his brother's victims, Gary Wright, a computer-store employee seriously injured by one of the Unabomber's homemade bombs. They have since developed a strong relationship.

Kaczynski said that the demonization of people like his brother and Cho is problematic because it prevents future progress. "[It] doesn't get us anywhere," said Kaczynski. "It doesn't provide us with solutions."

"I suppose in a sense we are surrendering our responsibility," said Kaczynski. "If we are just saying this guy was evil, a monster, in effect we are throwing up our hands and saying there is nothing we can do."