Some of us not-so-ancient Jews aren't squeamish about it, either.
You've got to be extraordinarily careful that the person actually did the crime, but once that's established its hangin' time (or shooting, or the chair, or injection, etc.). Scum like this don't deserve to live, and we in the rest of society don't deserve to have them still around, costing us money better used to help the unfortunate and with the risk of further violence as the result of an escape and/or parole.
“You’ve got to be extraordinarily careful that the person actually did the crime,”
Yes, that is the one essential caveat we need to apply. And, by social and technical means we have been less willing and able to do that, in the past, with as much due-diligence as we try to apply to these circumstances today.
But the errors in the means, the due-diligence means, do not refute the principal in the ends - some people have so broken and endangered their civil commitment to everyone else, that the socially moral thing to do is to rid society of them, with finality.
In many ways I am not really opposed to life imprisonment without any chance of parole, but the other mugwump side of me realizes that others use that approach to extend the possibility of, maybe someday............