Adam Lanza (April 22, 1992 - December 14, 2012) was the perpetrator of the December 14, 2012 massacre at Sandy Hook Elementary School in Newtown, Connecticut, in which he murdered 28 people and injured at least eleven more. After killing students and administrators, he commited suicide. His brother, Ryan Lanza was taken into custody for questioning. Adam's mother, Nancy Lanza, was shot by her own son at their house in Newtown, CT. The school's principal, Dawn Lafferty Hochsprung and the school's psychologist, Mary Sherlach were also killed. Twenty children were murdered in the shooting. A seven-foot spreadsheet was found in his home detailing virtually every single mass murder and attempted mass murder in history. Lanza was raped by a Catholic priest when he was young, then suffering in silence for years, seemingly acting like he was normal, but bent on vengeance against Catholics. Years later he would show the Catholics that their children won't be protected as well, killing 20 of the kids at Newtown just before Christmas. Like most mass murderers, Lanza was frustrated with his life, and he wanted to take as many people down with him as he could. He hoped to outdo everyone on this list, particularly Anders Behring Breivik.

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