The FBI has released new information that provides insight into the man behind the Sandy Hook massacre.
A woman who befriended Adam Lanza online prior to the 2012 shooting said he was "focused and obsessed with mass murders and killing sprees."
She also said Lanza spent most of his time researching and discussing mass killings.
Lanza killed 20 first graders and six adults at the school. He also killed his mother at their house before taking his own life.
FBI releases new information about man who committed Sandy Hook Massacre
U.S. & WORLD
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