Adam Peter Lanza, was the believed perpetrator in the Sandy Hook Massacre. He and his mother lived in Sandy Hook, 8 kilometers from the school itself. He did not actually have a criminal record, nor any infraction with law enforcement.
He was a student at the school for a short time, but was then transferred to St. Rose of Lima Catholic School, and then Newtown High School, where he was an honours student in English and Mathematics. He was apparently supposed to be homeschooled, by his mother, but the plans to do so fell through.
Students and teachers who knew him in high school described Lanza as "intelligent, but nervous and fidgety". He avoided attracting attention and was uncomfortable socializing, and was not believed to have had any close friends while at school.  His brother, told law enforcement that Adam was believed to have a personality disorder and was "somewhat autistic". An anonymous law enforcement official, who was friends with his mother, Nancy Lanza, stated that he had been diagnosed with Aspergers, previously.
Knowledge with Firearms
Close friends of his mother, have testified that Nancy Lanza was an adamant gun enthusiast, possessing several guns. . She often took her two sons to a local shooting range, taught them, in particular Adam, how to shoot, in the hope that it would teach him some responsibility. Critics of gun ownership, claim to this as evidence that guns should be controlled.