Maybe neither?
The dean isn't that much at fault, there's a long way from hitting people in the face to stabbing them in the chest. The stereotypical schoolyard bullies that beat you up when you're younger because they are stronger and bigger than you don't all go on to become murderers. Sadly, wanton acts of violence among children and teens have ALWAYS been a part of life - you can't keep half the nation's youth in the stockade. It's sad that it came to this, but nobody could have foreseen it.