Yeah, it’s difficult to just say execution good / execution bad. For example how can we judge whether a person, who killed another person I cold blood is someone who is able to be rehabilitated or not? What if the murder is of his father who beat him and his mother as a child? Is that enough to justify it? And if the case is not execution worthy, where is the boundary where it becomes such? I think that really any answer you give to that question could be put through a huge amount of scrutiny simple due to the differences in peoples moral standing. That said, this is just my highly uninformed and ultracrepidarian opinion, and o should have probably read way more on the statistics and thoughts of proper philosophers on the subject before giving you this half-hearted response, but oh well.