"Should be" is a really very much arguable statement in that last bit, MZ. Punshiment -- and removal from such concerns as mercy and pity definitely count, there -- is only something rightly invoked in a prescriptive statement when it has some functional benefit -- otherwise it's at best revenge and at worst base sadism. If re-integration is not intended, then punishment beyond removal (either by life imprisonment or execution) has no functional purpose -- revenge is certainly neither something societies particularly benefit from, nor something once enacted that does much for most victims.
It's strongly arguable that allowing people to act for vengeance or punishment instead of just or right action is deleterious -- especially on the net -- for the society that allows it. Stripping people of their rights in excess of necessity is definitely not just, nor right, and there are, indeed, some things you can't do to a murderer and retain the position of virtuous -- or even non-immoral -- action. No torture, no slavery, no rape, etc. Though a lot of penal systems have trouble with all of the above. Most of them are some of the most immoral and useless (fucking counterproductive, in many cases! Worse than useless) pieces of shit still allowed to function in a modern society. Understand the urge toward action beyond the necessary and functional (gods fornicate but do I), but right (i.e. "should be"), it is not.
Now, I might be convincible that a sex change op for a lifer isn't necessary, but that's a far different statement from saying that a murderer should have all human rights stripped from them.
Basically, do no harm except the necessary, and never in excess. Even for the worst of human filth, that rule should not -- must not, on an organizational or systemic level -- be broken. Doing so has caused more damage to our species than the collective weight of every murderer that's lived and died.