Capital punishment

Is capital punishment an effective deterrent or an inhumane practice?

I always thought it was inhumane but we now have the opposite. The poor rapist gets taken care of while they kill the victim. Let us help you with euthanasia because your life is ruined. For extreme war criminals for instance, they also did that after WWII. Is it that so bad?

I'm not sure how I feel about it really. I have always thought that people can learn better behavior, but now I'm not so sure.

For instance that serial killer who got saved but wants to stay in prison for the family, son of Sam, great that they didn't kill him, but some unrepentant monster, I don't really care.