Just to explain my earlier remarks that execution is not rational,
I agree that there is absolutely no place for them in society, but I don't agree that society has a right to decide that they should die. I think society is basically an artificial construct, a "social contract" of responsibilities and privileges that those of us who are "sane" agree to participate in and abide by. When someone chooses not to respect that contract I don't think they deserve to die, I think they deserve to not be permitted to participate in society, and I think that society has a right to protect itself from those people by removing them from it. The easiest way to do that seems to me, to be imprisonment.
I find it difficult to discriminate between personal murder and execution; execution seems like it could just as easily be referred to as state-sanctioned murder. If a person violated the rules of society by killing someone else, then it seems logically inconsistent to me that society would violate its own evaluation of life by ordering the death of a person.
I don't necessarily expect that society will behave rationally, or that behaving rationally is necessarily the best thing, as there may be other considerations; I just express these things as thoughts that are important to me.
Whether society has a responsibility to provide these people with some level of bearable quality of life is not something I have thought through rationally with any level of detail because it's just a humane belief that I have held which I haven't really questioned until now. (Although now that I have thought of it, I will question it more.)
My personal circumstance is having spent my life so far cohabiting with a parent who has complicated psychiatric problems as a result of countless childhood rapes. So I do understand wanting to kill someone over this, because I have wanted to kill someone over this on many different occasions. These are just my philosophical perspectives on the relationship between society and these people.