You aren't seriously asking if you could just shoot someone, holster your gun and go on your merry way like the wild west, are you?
Yeah, but it sounds crazy when you say it like that. If you shoot a BG and he survives, you clearly have an obligation to alert the police so they can find him and get him medical treatment, otherwise you are in danger of getting pinched for manslaughter. If you shoot a BG, and he goes down stone cold dead, is there a law requiring you to notify police of your not having commited a crime?