I don't think it's just coincidence that the number of these mass murders by young males coincides with the rise shooter video games. The military uses them to train our solders so they must think they're a pretty useful tool to train to kill. And although I have played them in the past and think they're a lot of fun I also think they should be sold like alcohol with sales only to adults 21+.
http://www.businessinsider.com/adam-lanza-played-call-of-duty-2012-12
http://www.businessinsider.com/adam-lanza-played-call-of-duty-2012-12