New details are emerging about Adam Lanza and how spent his time in the lead up to the massacre that left 20 children and 7 adults dead.
A source with knowledge of the investigation tell CNN Lanza "was obsessed" with mass murderers.
One of those, according to CBS and The Hartford Courant, is Norwegian mass-murder Anders Brievik, who killed 77 people in 2011.
Reporters for the Hartford Courant and CBS also say a trove of violent video games were found in Lanza's basement and that he played them all the time.
OutFront tonight: Professor of Criminology at Northeastern University Jack Levin, and Harvard Medical School Psychologist, William Pollack.