One view to which the rebuttal would be to lock them up for the rest of their lives in solitary confinement so they can't harm anyone again. Another view is that human life is so sacred, it is unjust for someone who brutally snuffed out a human life to continue to enjoy any of the pleasures of life himself.
the only problem is that these same people get their panties wadded up over this inhumane treatment, because the killers dont get to socialize and it causes mental problems ...
If they remain alive, there is always a chance that they will walk the streets again, among our children...