The father of the gunman who killed 26 people at a Newtown, Connecticut, school in 2012, said he wished his son had never been born, the New Yorker magazine reported on Monday.
Speaking publicly for the first time, Peter Lanza, father of shooter Adam Lanza, said: "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."
Adam Lanza, 20, shot and killed 20 first-graders and six staff members at Newtown's Sandy Hook Elementary School in December 2012. Lanza, who committed suicide, also killed his mother, Nancy Lanza.
The rampage was one of the worst incidents of gun violence in U.S. history and sparked a national debate on gun control and school safety.
Peter Lanza told the New Yorker that he wished Adam had never been born and that there could be no remembering who he was, outside of who he became.
"That didn't come right away. That's not a natural thing, when you're thinking about your kid. But, God, there's no question," Lanza, a vice president for GE Energy Financial Services, said in one of a series of interviews with the New Yorker that started in September.
"I want people to be afraid of the fact that this could happen to them," he said.
Peter Lanza said he had dreamed about Adam every night since the shooting, mostly with sadness rather than fear. But recently, he said he had the worst nightmare of his life.
He was walking past a door and a figure in the door began shaking it violently. Peter could sense "the worst possible evilness," saw upraised hands and realized it was Adam.
"I couldn't understand what was happening to me. And then I realized that I was experiencing it from the perspective of his victims," he said.
Lanza said that by the time his son entered middle school, it was clear something was wrong. Adam Lanza was socially awkward, anxious, unable to concentrate and afflicted with insomnia.
Adam Lanza was diagnosed with Asperger's syndrome, a high-functioning form of autism, at 13. But after a severe reaction to an anti-anxiety drug, he refused to take any more psychotropic medication.
Lanza said the Asperger's diagnosis may have been masking schizophrenia.
Lanza's parents divorced in 2009 and his father had not seen his son for more than two years at the time of the killings, he told the New Yorker.
"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," he said.
"The reason he shot Nancy four times was one for each of us: one for Nancy; one for him; one for (older brother) Ryan; one for me."
Lanza declined to say how his son's body was disposed of.
"No one knows that. And no one ever will," he said.
(Reporting by Ian Simpson; Editing by Bernadette Baum)