For every cast-iron 100% clear cut case, there will be other cases that are borderline and lead to a miscarriage of justice. While there is that slimmest of risk, in our society in this day and age, the death penalty will not be brought back.
Re: Also someone had to be the executioner. I don’t think we should be in the business of either putting someone in that position or encouraging anyone who is happy to do it.
there will be people like the OP who are willing to participate in ending the life of someone who commits a heinous enough crime to warrant the death penalty. Nowadays it would most likely be 10 people pushing a randomised button that administers a lethal dose to end the criminal's life that nobody ever gets to know whose button actually did the deed. Rather than an Albert Pierrepoint-like character.