That's what I'm suspecting. I wouldn't be too surprised to hear that this kid had been tormenting this guy constantly, and he snapped.
With what I know now, the best outcome is this: Guy pleads guilty to manslaughter, gets fifteen years, dies in prison, and parents warn their kids to stay the f--- off of other people's private property.
This is what I've tried (or did try) to explain to my sons all their lives. If you go around asking for it, sooner or later you're going to run into someone who will be that crazy and give it to you. My youngest in particular always seemed to have a chip on his shoulder and would do stuff like this. Sure, the guy was wrong and will pay, but the kid is still dead. What part about "leave people alone" don't kids seem to get.