Sandy Hook shooter Adam Lanza had an interest in children that could be characterized as pedophilia, but nothing suggests he acted on it, according to an FBI behavioral analysis.
A summary of the analysis was among the roughly 1,500 heavily redacted investigative documents released this week by the FBI, which painted a disturbing portrait of a reclusive young man who appeared to have no friends or people to rely on for support.
The behavioral analysis report, which was shared with the victims' families, did not specify the evidence of Lanza's apparent sexual interest in children. A file on Lanza's computer advocated "pedophiles' rights and the liberation of children," one document noted.
A separate FBI document said one of three CDs taken from Lanza's home contained pornographic images.
Another document said that an unidentified woman who befriended the killer online told investigators that Lanza said adult-child sexual relationships could be "possibly beneficial to both parties."
The woman began online contact with the troubled youth about two years before his December 2012, rampage at the Newtown, Connecticut, school left 20 first-grade students and six adults dead.
FBI: Lanza did not 'snap,' engaged in careful planning
The behavioral analysis determined that Lanza did not "snap" at the time of the massacre but instead engaged in careful, methodical planning and preparation. Evidence suggests he began contemplating the killing spree as early as March 2011, according to the documents.
In the weeks and months before he opened fire at his old elementary school, Lanza's deteriorating relationship with his mother was "a significant challenge and stressor in his life," the analysis said. He killed Nancy Lanza in their Newtown home before the school shootings.
"The shooter shared many similar characteristics and behaviors with other active shooters," the document said. "There is no evidence to suggest that the shooter viewed the attack as a 'video game' or as a contest."
Lanza's mother described as 'gun nut'
Lanza used a Bushmaster Model XM15-E2S rifle during the shooting spree, which ended when he shot himself.
The rifle and two handguns -- found next to his body -- as well as an Izhmash Saiga-12 12-gauge semi-automatic shotgun recovered in his car were legally purchased by his mother, whom the documents described as a "gun nut."
The woman who befriended Lanza online said he was "singularly focused and obsessed with mass murders and spree killings" and looked upon school shooters "with respect and understanding," according to the FBI documents released Tuesday.
"The weirdest person online" she said of Lanza, who "devoted almost all of his Internet activity to researching and discussing" mass killings he meticulously documented and viewed as "a symptom caused by a broken society," according to the roughly 1,500 investigative documents.
The woman told investigators that Lanza was "extremely intelligent" but depressed and cynical, with a negative and rigid view of the world.
Lanza's online posts included screen names that referred to German and Canadian school shooters Tim Kretschmer and Kimveer Gill, according to the woman.
The woman said Lanza "seemed to wallow" in his depression, riding out low moments in his room and sleeping for 12 hours or more, according to the documents.
Lanza avoided daylight
The documents said Lanza found food unappealing and complained about being unable to find clothing that fit him comfortably. Saying that natural light hurt his eyes, Lanza avoided daylight and spent a lot of time at home, the documents said.
One document described an interview in which neighbors told the FBI that agents had once visited the Lanza home after he hacked an unidentified government computer when he was in the ninth grade.
Lanza successfully made it past two levels of security before the computer screen went black and agents appeared at his door, the document said.
"Nancy had to convince the authorities that her son was just very intelligent and was challenging himself to see if he could hack into a government system," the document said.
"The authorities told Nancy that if her son was that smart he could have a job with them one day."
Lanza's online friend told investigators that he revealed little about his family and personal life. He liked to portray himself as someone who lived an isolated existence "in which he was always in discomfort," the documents said.
Lanza told the woman he believed he could be "asexual" and that he was sexually attracted to one or two people during his life. The documents said he viewed successful people as "selfish, cruel and controlling," according to the documents. He chose to be a vegan because people were "needlessly cruel" to animals.