Well, we are certainly not God to to commit somebody's life to an end, and really, people should pay for their crimes.
I say, a long-life imprisonment would do better than fine to anyone who's done some serious crime!
Imagine denying common rights to those who don't deserve them (I mean, if you wanna be part of the society, you gotta suit yourself to that society). Why giving rights to those who simply abuse them.
Simply like this (and kind of fictional): In the Harry Potter series, Azkaban's the place where not even the toughest criminal wants to end up in, so if we had a place like that (maybe Guantanamo), criminals would think twice before committing murder or something of the like.
Instead of ending somebody's life, they should pay their debts with their own flesh and sweat, their own suffering and fear.
Kind of cruel, but using this method in a mentally way, it can do things to you. Attacking the mind seems more effective than attacking the body.
In a hot topic like this, there's not right or wrong, only two different opinions about handling criminals and their actions.

Trying to find somebody with same ideals. Through experience, we realize what we really want at the end. So dating many people is a good thing when you do it the right way!