Watch this film for a different take on it,
http://en.wikipedia.org/wiki/Elephant_(2003_film)">http://en.wikipedia.org/wiki/Elephant_(2003_film)
Which is to say everyone will look for something in particular blame, when there isn't an easy answer. There are kids who play violent games that don't shoot people, kids who use firearms that don't shoot people, kids who are depressed who don't shoot people, kids that are bullied that don't shoot people, kids who are introverted that don't shoot people. None of these things alone or together could explain the shootings.
7 minutes ago, Ray7 wrote
*snip*
How come the parents didn't spot this? They've known the kid longer than any of his teachers after all. They're the ones who know he's locked in his bedroom playing Judas Priest tracks in reverse. And how dangerous would the kid be if he didn't have such easy access to firearms?
It is not the teacher's job to raise children. That's down to the parents.
Speaking of that, a lot of people misunderstand the criticism against violence in games and movies. There was never an argument that perfectly normal kids would be warped by violence and go out wanting to slaughter people; so Moore didn't really address the issue seriously in his movie. The argument was that when violence was common, people would become "desensitized" to it and no longer see it as abnormal, so you could no longer tell when someone had a problem. There are no warning signs anymore if many kids are into it. Parents don't even know everything they're kids are watching or seeing, so they might not even be able to tell if there were a warning sign.
So -- so what if he was locked in his bedroom listening to death metal?