New chilling details of the Sandy Hook elementary school killer who took his own life emerged Monday: apparently, the alleged 20-year-old mass murderer Adam Lanza suffered from a rare condition that left him unable to feel physical pain.

Richard Novia, the advisor for the tech club at Newton High, Lanza's old high school, revealed to ABC News that if Lanza cut or hurt himself, "he would not know it or feel it."

Novia, who was then also Newtown school district's head of security, said that Lanza's disorder meant that he needed extra supervision whenever he handed equipment because there was a chance that he might unknowingly accidentally injure himself, according to the Daily Beast.

Novia recalled that Lanza's physical condition triggered psychological spells that made him withdraw so much that his mother would sometimes have to be summoned.

"He was very withdrawn and meek, he was one of those freshmen in very much in need of watching. He would have episodes where he would just shut down. He'd sit staring at the ground and refuse to talk to anyone," Novia told the Daily Beast.

"If that boy would've burned himself, he would not have known it or felt it physically. It was my job to pay close attention to that," Novia said.

Novia told the Wall Street Journal that while it was not unusual for troubled students to meet with school officials, Lanza's problems were more severe that most, to the point that he was assigned a permanent psychologist.

Novia said that he had assigned three security staffers to carefully monitor Lanza and report "where he was, who he was with, and what he was doing."

Lanza's former babysitter, Ryan Kraft, who took care of the elementary school gunman when he was nine-years-old told KCBS he started shaking when he heard that the young boy he used to watch had shot his mother in the face before killing 20 innocent children and six adults last Friday.

Kraft recalled Lanza's mother Nancy's chilling warning before she left him to take care of her young son.

"[She said] to keep an eye on him at all times...to never turn my back, or even to go to the bathroom or anything like that," he told KCBS.

Kraft said that Lanza was a very intelligent but quiet and introverted boy.

"Whenever we were doing something, whether it was building Legos, or playing video games, he was really focused on it. It was like he was in his own world," Kraft said.

Not long before the Lanza's murderous rampage, his mother had reportedly confided in a friend over drinks that her troubled son was spiraling out of control.

"I don't know. I'm worried I'm losing him," the friend who wished to remain anonymous quoted Nancy as saying, according to the Daily Mail.

"Nancy told me he was burning himself with a lighter. In the ankles or arms or something," the friend said. "It was like he was trying to feel something."