Its not the game which makes a killer it's their state of mind.
I played with toy guns, soldiers and tanks, cowboys and indians as a child. I watched TV shows with all of these occuring. I was in the Defence Force for 19 years. I have played games since I was 10.
I didn't turn out to be a violent mass murderer.
The last mass murderer was home grown and a member of their Defence Force. He obviously has a screw loose. Just because he played games doesn't mean it was the cause of his instability.
It was always their.