I disagree strongly Amos. Society certainly deserves protection from this man. I would have had no more regrets than you if a law enforcement officer had shot him while he was attempting an assault. That is very different from saying we have the right to drag a helpless man (no matter how bad) from a cell and then slaughter him. One of the reasons that civilised lands abandoned this horrible practice was because of the the appalling effect it had on the prison officers and the officials responsible for carrying out the sentence. The fact that many sick/wicked/weak killers may deserve death is neither here nor there. In Britain I felt that the Birmingham Pub Bombers deserved execution. I still do. As it happened, the authorities jugged the wrong people and banged them up for years. One of them even died inside, I believe. Thank God we didn't execute them. I doubt if my admission of being wrong and saying sorry is much use to those whose lives were ruined. I sure am glad that wiser heads than my own prevailed at the time.
When justice becomes perfect, we will be able to carry out capital punishment with a clear conscience. The conundrum is that when justice is perfect, it will mean that people are too. So capital punishment will be both unecessary and unwanted. For the time being, let's just stop this horrible practice anyway. No civilised country carries it out.