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(CNN) – For the first time, there is some insight into Sandy Hook gunman Adam Lanza's deteriorating mental state, and the warning signs that led up to the massacre of 26 children and teachers, from one of the people who knew the intimate details of Adam's struggles – his father Peter.
Peter Lanza breaks his silence in an interview with author Andrew Solomon featured in this week's New Yorker issue .
"He felt having been hounded for his story, that perhaps telling it could be helpful to the families who had lost children at Sandy Hook," Solomon said in an interview with CNN's "The Lead with Jake Tapper."
Lanza also thought that sharing his story would "cause the FBI to have a better sense of how they could avoid events like this in the future," Solomon says.
Peter Lanza had read Solomon's book "Far From the Tree: Parents, Children and the Search for Identity," which tells the story of the Klebolds, the parents of Columbine shooter Dylan Klebold. Lanza found Solomon's writing fair and just, and reached out to him in September.
When Adam Lanza got to middle school, "it was crystal clear something was wrong. The social awkwardness, the uncomfortable anxiety, unable to sleep, stress, unable to concentrate, having a hard time learning, the awkward walk, reduced eye contact. You could see changes occurring," Peter Lanza told Solomon.
But experts said they didn't see anything violent in Adam.
Peter Lanza "did as much as he felt able to do. And in retrospect I think he wishes he had done things otherwise," Solomon said.
But Lanza also said he doesn't think that the catastrophe could have been predicted.
"Adam saw a number of highly qualified psychiatrists, all of whom thought he was a very disturbed young man, none of whom thought he would injure anybody else, or be violent or harmful to others," said Solomon.
One of the most striking comments in The New Yorker interview, is when Lanza says he wishes Adam had never been born.
"Peter still does have love for Adam," said Solomon. "But he sees a balance, in which his love for Adam is put in a scale against the horror of what Adam did. And of course Adam's crime is particularly, singularly horrific."
"His feeling is that though he still has affection for Adam, that he really, he would love to be able to erase that part of history," said Solomon.
There are many people who are angry with the Adam Lanza's parents, and blame them for not doing more to prevent the attack.
"I think we're all very angry with Adam Lanza, and I think we'd like to be able to blame his parents for what went wrong," said Solomon.
"Should his parents have insisted that he have more therapy? Perhaps. Should he have been on a different medication? Perhaps. But I think the decisions they made, the relative mix of laissez-faire and indulgence, is a mix that's often worked well for people who have the kind of mild autism that Adam had.
"It's difficult while you're in that situation to understand what will come next," said Solomon.
For more of our interview with New Yorker contributor Andrew Solomon, check out the video above.