Sitting firmly on the fence here, but it depends on your point of view; is jail time a form of punishment, or an 'opportunity' for rehabilitation? I can't say I've done a lot of study on re-offending rates of long term prisoners and the like, but it really does just depend. Obviously some people are beyond rehabilitation, and not necessarily for reasons of mental health. Some have said the death sentence is OK (FWIW I'm amenable to it in principle) for serial killers/mass murderers etc - who's to say they don't suffer from the same mental afflictions as this bloke?!