People should research the legal/prison system in Norway before they say anything about this. The American prison system is much about retribution, whereas Norwegian is about rehabilitation. The Norwegian prisons are luxurious compared to the US prison. Look, here's a picture of a Norwegian prison 'cell':
The inmates study, they have access to internet, they execrise hobbies. It's basically a supervised motel that you can't get out of whenever you want.
There is no life-sentence in Norway, the max determinate penalty is 21 years in prison and only a very small fraction spend that. The maximum sentence for "crimes against humanity" is 30 years. Prisoners usually get unsupervised parole on weekends and such after serving about a third of their sentence. There is a possibility of serving a lifetime in prison with "Containment", which is set for the standard 21 years, but can be prolonged if the prisoner in question is still considered dangerous. However, they could be released, either from prison entirely or just on parole, after 10 years of serving the sentence if they are no longer considered a danger to society.
Psychiatric Ward however ensures that he'll be there for his lifetime. To people who go "they should just let him rot in jail for the rest of his life!", if you're that hell-bent on revenge and retribution, this solution should actually be preferable to you.