I agree... this is way out of control. Even when i was in high school I used to draw violent stick figure drawings as a means of relieving stress. Hell, half my teachers found them as funny as I did. I even made personalized ones to give to friends. Welcome to the new neoconservative America, where money talks, and the first ten amendments walk.
Seriously though, what charges are they being held for? The only thing that could even come close is assault, and even that is hard to press since there was never any verbal threat, nor was there any explicit writings detailing a possible threat. A figure drawing tends to not stand up in court, outside of deciding sanity.
I hope the kids get out, and the parents sue the living fu[i][/i]ck out of the school. That was a horrible way to handle things. Those kids, if anything, should have been sent to see the school social worker or shrink.