"I mean, he was the first real Christian that I'd ever met that really did what Jesus Christ told him to do," he said. "You know, I'm very tough on a lot of Christians as being hypocrites, even though I am one myself ... and while there was a side of me that was wanting to just shout, 'It's me, it's me, forgive me!' I couldn't do it. I wasn't strong enough at the time."
Bart fled to Mexico when police began to close in on him as a suspect, but he now says he's accepted the punishment he's received.
"I don't think you can live [on death row] and not want to be here," he said. "But on the other side, if you were to open that door for me, I wouldn't leave. ... The only way I get through living day to day is knowing that I'm paying off a portion of that guilt minute by minute."
He now claims he's a changed man, a change he says began immediately after the shooting.
"I lay on the floor in my blood. I would say that's when it started," he said, adding that the change continued during his time in Mexico.
"I became very simple in Mexico," he said. "There was all of the wastefulness that I had exhibited in my prior life, the Ferragamo shoes and the expensive stuff all became meaningless to me down there."
He knows some people may never accept that he's changed or offer him forgiveness.
"Would I like to be believed? Certainly. But what's important to me is that in these last years I try to do something good for somebody, and that doesn't require that I'm believed or not," he said.
Dr. Edward Hallowell, a child and adult psychiatrist and an expert in parenting and the importance of connection and forgiveness, says Bart is an example of "the power of disconnection," after watching a tape of his interview with ABC News.
"He didn't feel the love from his parents, from his brother, from family friends that he needed to feel," Hallowell said. "He's reading existential philosophy at the age of 9, he's feeling cut off, set apart from others, he has loving parents and brother and yet he's feeling rejected by them. And this to me, it's just a glaring statement of the power of disconnection."
Hallowell said he might classify Bart as a sociopath and a narcissist based on his answers, tone of voice and body language in the interview.
"He seems like a very empty human being," Hallowell said. "And it's very tempting to speculate, you know, that, that he is what we call a sociopath. ... He seems singularly without remorse and without even the beginnings of remorse. And he sort of mouths the words, but you don't feel it.
"And as for narcissism ... people think of that as being ... self-centered. It's more simply that you're empty," he said. "You don't have the ability to give and receive love."
Hallowell went on to say that normally, people who become sociopaths grew up in environments where they were exposed to extremely traumatic events. But Bart clearly grew up in a safe, loving, generous household.
"I think we have to look at sort of new research that's coming along saying that, that some people are born with a nervous system with a, with a whole wiring that is just a little bit off, a little bit different, more susceptible to rejection, for example," Hallowell said. "[Bart] felt tremendously rejected and inferior, even though there was no reason, external real reason, he perceived rejection. And that may be just ... in the DNA."