Bethea was shot in the "hand, head, chest, and buttocks". One shot is a righteous shoot. Four shots is an execution. You have to remember that this was .22 rimfire. You could take a large number of shots to stop someone, especially someone on drugs. Chances are you could shoot someone 4 or 5 times and they'd keep on keeping on for quite some time. This perp was just unlucky, as one or more of the bullets managed to hit something vital.
I think this is rather strange. A man, angry because someone is breaking into his car, grabs a 22 rifle and goes out to confront the perpatrator on a city street. Upon being confronted, we don't know just what the perp did. Did he stay put and argue with the owner as the rifle muzzle comes up? Was the owner close enough to shoot point blank? It doesn't sound like the perp attempted to run away or disengage from the situation, as otherwise he would have been shoot in the back (unless this is where the buttocks come in). I don't believe they indicated what time of day this event occurred, so we don't know if other people may have been endangered by an angry man shooting a rifle down a city street.
Also, I note that we know that the "vigilante" does not have a previous crimminal record, yet we know nothing about the crackhead.