Of course Thou shalt not kill. I am in no way excusing the big jerk. But the little jerk who had a history of assaulting a police officer was not blameless in his own death. Sooner or later he was going to run into someone that would give it right back to him. Sadly, for all concerned, it was sooner.
BTW, the only one in that group that seemed to have any decency was the grandfather. Interesting family dynamics. I'd love to know the story. If dead dad's kids go bad I bet it will all be blamed on incarerated dad.