Ahem. Right. Yes, I am being totally facetious and snarky.
From a very good article on Gamasutra: Video games and gun violence: A year after Sandy Hook.
It's extremely in-depth, and well worth reading. And as to the origination of the snarkiness, here it be:
In November 2013, the Sandy Hook report was finally released, detailing what the authorities had discovered about Lanza and his motives for the shooting. It was a 44 page report, describing the event and what is believed to have been the cause of Lanza's rampage -- but you'll have to scroll a fair amount to find any mention of video games.
That's because, as discovered, Lanza didn't really have any out-of-the-ordinary desire for violent video games at all. Sure, he played them -- the likes of Call of Duty, Battlefield, and Grand Theft Auto were found in his basement -- but if anything, he actually had an obsession with a certain non-violent video game: Dance Dance Revolution.
"The GPS found in the home and reportedly belonging to the shooter indicated that he regularly went to the area of a theater that had a commercial version of the DDR game in the lobby," it continues. "In 2011 and up until a month before December 14, 2012, the shooter went to the theater and played the game. He went most every Friday through Sunday and played the game for four to ten hours."
"One of the things that really struck me was it mentioned that he wrote about fantasies of violence for his teachers," adds Olson. "There was just one teacher saying she was really upset about it, it was so graphic she didn't want to share them with other people. That is something you saw with the Virginia Tech shooter as well -- violent fantasies being handed into teachers."
"That's the thing: The typical teenager, especially male, is playing a violent video game on a regular basis, but I don't think the typical teenager is writing about graphic violent fantasties and handing them to people."