The summary says Lanza had “significant mental health issues.”
The report said that in 2005, Lanza was diagnosed with Asperger's disorder, a mild form of autism that is not associated with violence, and that he lacked empathy for others and behaved strangely.
Nobody was allowed into his room, he wouldn't touch doorknobs, his food had to be arranged on the plate in a certain way and he changed clothes often during the day, according to the report.
As a child, Lanza wrote “The Big Book of Granny,” in which the main character has a gun in her cane and shoots people, and another character talk of liking to hurt people, especially children.
The book was among items seized from Lanza's home, but there was no indication he ever handed in the book at school.
Lanza became obsessed with the 1999 shooting at Columbine High in Colorado and other mass killings, the report said. He kept a spreadsheet ranking mass murders.