Illini,
1. Not always. Video games can be a trigger and also help to desensitize. Why do you think the military uses video games to train soldiers?
I'll simplify this. When you play video games, you get a feeling of euphoria - it's fun. You're becoming something you're not, whether it's an orc, an NBA player, or a soldier fighting aliens. You like the euphoric feeling, so you play more and more. You prefer violent, first person shooters. You feel good playing that game. It's comforting, as you have no friends. You think everyone is out to get you, so you think it's cathartic to shoot all these people in a game instead of real life.
Eventually, that video game is a drug and you're addicted. Like any drug, you develop a tolerance and you seek bigger and bigger highs and dosages. You're desensitized to the violence, and your mind begins to blur the lines between reality - consequences for shooting someone, for instance - and the game. You seek greater and greater highs - more realisitic graphics, physics, and plot lines. You withdraw completely, cutting yourself off from reality aside from required tasks, such as going to school or work. One day, something happens that completely destroys the line between video games and reality, and you snap. You get a gun that you bought because you thought everyone was out to get you, and you see your enemies' faces on everyone, and you shoot them. You are hallucinating, and killing those people feels good, it's an adrenaline rush - the ultimate high. You've finally achieved the best high you could possibly get, and you know it. You turn the gun on yourself...
It's dumbed down a bit and I wrote it quickly, but you get the idea. It can happen - video games can be an enabler, and in some cases, a cause - but typically, a person is a loner, violent, and troubled far before they ever touched a keyboard or picked up a controller.
I believe that video games typically do not cause violence any more than the 5 o'clock news or the Jerry Spring Show.
2. Read a few articles. He was being taught privately because he scared one of his professors. They knew about him, but if you profile every mentally unstable kid to snap into a pyschotic rage, well, that's a an even bigger can of worms than gun control.
3. Doctors and therapists are required to know about chemical imbalances; if they didn't, they wouldn't be able to be what they are - especially therapists, as a therapists deal with mental illnesses, and those illnesses are typically caused by chemical imbalances. Teachers are trained to watch for signs, but most state laws prohibit them from doing anything unless there are signs of abuse, the student is a disturbance, or they ask for help. It sounds like this guy wasn't any of the above; he wasn't a disturbance; he just creeped people out, and I can name 10 people that creep me out - but I don't think they're going to go crazy. He certainly didn't ask for help, and there were no signs of abuse. Why would they?
Society thinks they know everything about these illnesses. They misunderstand everything, and think pills can cure all. To be honest, most mental illnesses can be treated by simply talking and doing things to raise one's self esteem. A drug only cures chemical imbalances - it should only be prescribed when the chemical imbalance can't be fixed by non-chemical means.
...and I'll get off my pulpit.