this is an archiac practice that has no place in a civilized society.
Removal of all rights and life in an environment with no stimuli is a better punishment. Rather than counting on the killer going to hell make a hell for him right here and now
Punishment by death alludes to the idea of sending the criminal to final judgement. But, we know now days that god would rather we deal with it, since he is too busy trying to be hard to prove/disprove