The perp is the exact opposite situation as the kid you mentioned. Classic juvie/delinquent situation. horrible homelife/background that caused it and enables it.One thing I strongly suggest is having your son talk to a counselor of some kind, whether a private one or the school one if they have one for elementary grades. You are probably correct that he is ok, but kids are pretty good at hiding feelings as well. Just make sure he has recovered mentally and emotionally.
I may have missed it skimming the thread, but is there anything special about the perp? We had a kid that was a good athlete at least for our school, but never great really. Making it to state wrestling but never hit the podium, which when you think about all the classes and weights, a lot of kids make it to state wrestling. He perversely assaulted a kid in PE class where there were no cameras. Nothing happened to him but when the kid knocked him, it was right in front of a camera. Original victim finished high school at alternative school. Any marginal athletic ability means a kid can get away with anything here.
I have some compassion for his situation, but the limit of that stops at my son's well being, obviously. It's perplexing.