This is the killer, Adam Lanza.
This is how he described:
Family friends in Newtown also described the young man as troubled and described Nancy (the mother) as rigid. "[Adam] was not connected with the other kids," said Barbara Frey, who also said he was "a little bit different ... Kind of repressed."Washington Post
A really rambunctious kid, as one former neighbor in Newtown, Conn., recalled him, adding that he was on medication. He was a son of an accountant and a schoolteacher. A family member told investigators that he had a form of autism, a law enforcement official said.NY Post
“He was smart,” the insider said. “He was like one of these real brainiac computer kind of kids.”
A “longtime” family friend said Lanza had a condition “where he couldn’t feel pain.”
“A few years ago when he was on the baseball team, everyone had to be careful that he didn’t fall because he could get hurt and not feel it,” said the friend. “Adam had a lot of mental problems.”