As the police combed through his home after the shooting, they discovered Ms. Lanza lying dead in a bed in a second-floor bedroom with a gunshot wound to her forehead and a rifle nearby.
They also found hundreds of rounds of ammunition and a host of weapons in a brown safe and in bedroom closets. The police also discovered numerous books related to autism, including one titled "Born on a Blue Day – Inside the Mind of an Autistic Savant." Another book was called "Train Your Brain to Get Happy."
Neighbors and classmates of Mr. Lanza have said he had an autism variant known as Asperger syndrome, though investigators have never confirmed that he had such a diagnosis. Even so, his association with the disorder have raised alarms among parents of children with the diagnosis, fearing it may be associated with violence.
Experts say individuals with autism spectrum disorders are often bullied in school and the workplace, and frequently suffer from depression, anxiety and suicidal thoughts. But the experts also say there is no evidence that they are more likely than any other group to commit violent crimes
The police also found a certificate from the National Rifle Association bearing the name Adam Lanza, and an N.R.A. guide to the basics of pistol shooting.
Among other items police officers found were seven journals written by Mr. Lanza, along with several of his drawings. The contents of the journals or the nature of the drawings was not disclosed. They also found three photographs of what appeared to be a dead person covered with plastic and what appears to be blood, and a New York Times article dated Feb. 18, 2008, about a school shooting at Northern Illinois University in DeKalb, Ill. In that shooting, Steven Kazmierczak killed 5 people and injured 21 on Valentine's Day before he killed himself.
The day of the Newtown shooting, agents with the Federal Bureau of Investigation interviewed a person who said Mr. Lanza rarely left his home. The person, whose name is redacted, considered Mr. Lanza to be a "shut-in and an avid gamer who plays Call of Duty, amongst other games," a law enforcement affidavit accompanying the warrants stated.
http://www.nytimes.com/2013/03/29/nyregion/search-warrants-reveal-items-seized-at-adam-lanzas-home.html?pagewanted=all