No.
If it was self-defense, yes (which is not murder). Anything else, no. Sorry. You murder someone, you’re out.
Same goes for close friends. I don’t believe that being a friend means becoming an accessory to murder. Murder is serious. It isn’t something you just do and forget about. It’s with you for the rest of your life. It would probably destroy our relationship and would probably destroy him. Even killing someone in self-defense can screw you up for life. It’s not something to be taken lightly. I couldn’t be with someone who thought it was okay to kill someone just because they wanted them dead.
Of course, my boyfriend is like the nicest, calmest, most non-violent person I know…