Peter Lanza keeps his family photographs in a box in his home office. He used to display them, he told The New Yorker‘s Andrew Solomon, but now he finds it too difficult to look at his son Adam.

“You can’t mourn for the little boy he once was,” Lanza said. “You can’t fool yourself.”

Lanza’s comments mark the first time he’s spoken publicly about Adam, who in December 2012 killed 26 children and adults at Sandy Hook Elementary School, his mother and himself. In the article, Lanza describes his own relationship with his troubled son, as well as the relationship between Adam and his mother.

Lanza described Adam as a talkative child, with a “sharp” sense of humor and a fascination with guns and World War II. Adam received an early diagnosis of sensory-integration disorder, but Peter recalled that Adam “loved Sandy Hook school.” His son was “just a normal little weird kid,” Peter said.

Things changed in middle school, when the structure of the school day changed and he moved from room to room for different classes:

… he found the disruption punishing. Sensory overload affected his ability to concentrate; his mother xeroxed his textbooks in black-and-white, because he found color graphics unbearable. He quit playing the saxophone, stopped climbing trees, avoided eye contact, and developed a stiff, lumbering gait. He said that he hated birthdays and holidays, which he had previously loved; special occasions unsettled his increasingly sclerotic orderliness. He had “episodes,” panic attacks that necessitated his mother’s coming to school; the state’s attorney’s report says that on such occasions Adam “was more likely to be victimized than to act in violence against another.”

Peter Lanza confirmed that his son had been diagnosed with Asperger’s syndrome — a diagnosis Adam refused to accept — and the article details the many times that Peter and Nancy sought professional help. Nancy “would build the world around him and cushion it,” Peter noted.

Lanza, who at Adam’s request hadn’t seen his son for two years before the shooting, said that he has had “gut-wrenching” meetings with two of the victims’ families. He said he was speaking publicly in the hopes that his information could help the families or help prevent a future event.

“How much do I beat myself up about the fact that he’s my son?” Lanza asked. “A lot.”

Sarah Moughty