I believe at one point he had something in his hands, the pipe?
Anyway, Weapon+intent+deliverly system= a good shoot
No one wants to do it but sometimes it needs to be done.
My quess with the tazer, they didnt get a good enough hit, he was a big boy, you are trying to shock the central nervous system (in the spine) his size may have insulated the tazer from having its full effect.