I agree with Garygaz in that, why should taxpayer's money go towards feeding and sheltering these criminals when, given the choice, they can just end their lives through consent. On the other hand, it is hardly a deterrent.
I would like to entertain the thought that these people, excluding the mentally ill, are very conscious of the consequences of their crimes when they are executed. But you could also argue that anyone in their right frame of mind, wouldn't commit a crime deserving of life in prison. I would imagine they are also aware of what their punishment in the particular country entails. It's not like Asia, where everything culminates in the death penalty (which I am completely against). At the same time, for example, if you're drug trafficking, you're aware of that risk of being caught and shot down. This applies to the discussed perpetrators.
The idea of a life sentence is inevitably married to the vindictive sentiments of the 'victims', which is exceptionally base and sickening. It's burning a hole in our pockets, equally. I suppose, these people can be sentenced to hard labour or community work, something to that effect, because at least, no one's dying and the moral/ethical issues aren't as ambiguous, they aren't perpetually confined to their cells and it's productive. I'd think.
Maybe? *morally conflicted coughs* - ahem -
Just thought I'd add a strange hypothetical. The question of euthanasia is choice, and we've come to the consensus that if you're imprisoned for life, you must have immensely screwed up. Suppose you give the prisoner a very sharp, pointy knife and this was legislated. Would this avenue of death in prison be allowed?