If you are dealing with a psychopath, someone truly evil that you know will keep doing bad deeds over and over you at least need to stop him/her.Absolutely not Wandering Star. I'm hugely ignorant in these matters, and have to fall back on my values and instinct. Calling for someone's execution feels like a failure of compassion to me. If you're telling me I'm speaking out of a lack of understanding I would certainly agree with that and will read further to educate myself on the the topic, but that's how I feel.
Jail ? When we know the mob keep running there business even inside, what kind of treatment could possibly be human and compassionate ?
Total isolation ?
There is no way I see that a 'human' treatment might apply to these people. It's difficult for people who can feel compassion to come to term with the idea that you are not dealing with a 'human' per say. More like an alien species.
I don't have the right answer to the situation but extra steps must be taken against very dangerous people IMO.