Adam Lanza's father speaks out: 'He would've killed me'

Adam Lanza took the lives of 26 people at Sandy Hook Elementary school, and now his father is speaking out for the first time.

Peter Lanza hadn't seen his son in two years at the time of the shooting. He says he wishes he would've pushed harder to see him, but that he thinks what happened would've been impossible to predict.

He spoke exclusively with The New Yorker, saying, 'You can't get any more evil ... How much do I beat up on myself about the fact that he's my son? A lot.'

Peter Lanza says that he's come to accept that from that day in December 2012 on, Adam was not the little boy he once knew - he'd become an entirely different person.

'With hindsight, I know Adam would have killed me in a heartbeat, if he'd had the chance. I don't question that for a minute. The reason he shot Nancy four times was one for each of us: one for Nancy; one for him; one for Ryan; one for me.'

Ryan is the family's other son, Nancy is the boys' mother - Peter's ex-wife - who Adam shot and killed, ABC reports.

Nancy was reportedly 'a woman that relatives say would've done anything to help her son if she knew he needed help.'

Peter agrees with that, saying he believes Nancy did not realize just how dangerous their son was.

He does say there were signs Adam was problematic from a young age - at first he seemed like a 'normal little weird kid,' but by middle school it was 'crystal clear something was wrong.'

Adam had anxiety issues and was unable to sleep, CBS reports. He'd exhibited interested in violence at that point. Nancy and Peter tried to get him professional help, but things got worse - eventually Adam cut off contact with Peter.

Now, Peter has nightmares about Adam, and ultimately says he wishes Adam had never been born.

You can read the article in its entirety on The New Yorker's website.