School adviser: Gunman a loner who felt no pain

Richard Novia, the school district's head of security until 2008, who also served as adviser for the school technology club, said Lanza clearly "had some disabilities."

"If that boy would've burned himself, he would not have known it or felt it physically," Novia told The Associated Press in a phone interview. "It was my job to pay close attention to that."

Novia was responsible for monitoring students as they used soldering tools and other potentially dangerous electrical equipment.

He recalled meeting with school guidance counselors, administrators and with the boy's mother, Nancy Lanza, to understand his problems and find ways to ensure his safety. But there were other crises only a mother could solve.

"He would have an episode, and she'd have to return or come to the high school and deal with it," Novia said, describing how the young man would sometimes withdraw completely "from whatever he was supposed to be doing," whether it was sitting in class or reading a book.

Adam Lanza "could take flight, which I think was the big issue, and it wasn't a rebellious or defiant thing," Novia said. "It was withdrawal."

Authorities on Saturday continued a wide-ranging investigating into the second-deadliest school shooting in U.S. history, trying to understand what led the young man to kill his mother in their home and then slaughter 26 children and adults at a Connecticut elementary school before taking his own life.

A law enforcement official, speaking on condition of anonymity because the person was not authorized to discuss the unfolding investigation, said Lanza had been diagnosed with Asperger's, a milder form of autism. People with the disorder tend to function poorly socially but can be highly intelligent.

If he did have Asperger's, his lack of sensation could be related to the disorder, said psychologist Elizabeth Laugeson, an assistant clinical professor at the University of California, Los Angeles. People with Asperger's can be overly sensitive to things like touch, noise and pain, or sometimes under-sensitive, she said.

Back in their teenage years, Adam and his older brother, Ryan, were both members of the tech club, which offered students a chance to work on computers, videotape school events and produce public-access broadcasts.

It was popular among socially awkward students. But Adam, while clearly smart, had problems that went beyond an adolescent lack of social skills, Novia said.

"You had yourself a very scared young boy, who was very nervous around people he could trust or he refused to speak with," Novia said.