Yes it's obviously video games fault/sarcasm. Ok, really, why do people keep posting these things on the escapist? Every week or two there's a new "video games are the devil" thread. we already know that none of us agree with this crap, and it's already been pointed out that the studies are all poorly executed and use suspect methodology, and that there are just as many studies that dismiss the effect as having nothing to do with the medium, and instead being related to competitiveness of the game in question, or whatever.
No, games do not cause this. The kid made the decision to do it, probably because his parents hadn't raised him correctly, or maybe because he was born a psychopath or a sociopath or something. It has nothing to do with the game. In a similar situation, the kid would have done the same thing if his parents had kept him from playing soccer, or from getting his driver's licence, or from going out to a party with his friends. Human beings are passionate about the things they care about. If they aren't taught how to control those passions, or if they have a emotional imbalance, they react poorly and immorally and do stupid shit like killing people.
This has nothing to do with whatever passion they were feeling at the time, and everything to do with the individual involved.
Put two boys that love CoD in a room with console, and let them play. Then put two other young boys in a room with a bunch of normal toys, and two sticks. Lets see who gets violent first, and who gets more violent. My money is on the two boys in the room with sticks every time for both counts.
Human beings are violent creatures, and that's just the way it is. People who blame video games, or movies, or Rock Music, for people who act on this violent urges are just trying to deny the violence in their own nature, and such an assertion says much more about the person who makes it, than about the person who committed whatever crime "because of video games."