Bastards like this give Lunatics a bad name.
Personally, I've always wondered about why some countries (like the USA) let crazy people off. Consider these 2 scenarios:
Murderer #1 has been tormented for the last 10 years by someone in who is in a powerful enough position to be untouchable. He finally decides the only option is to carefully plan out a killing, awaiting his victim in a dark alley. It's an almost perfect crime - except for that new security camera.
Due to pre-meditation and waiting for his victim, he can't claim temporary insanity. Instead, he gets the death penalty. If he's lucky, he can get that turned into a life sentence (best case - he gets out in 20-25 years depending on what jurisdiction he's in, worst case - life without parole).
He's not a threat to anyone else and had a hell of a motive.
Murderer #2 is deeply disturbed. His condition is untreatable, but he keeps getting discharged from the local psychiatric unit since they can't keep him forever and he doesn't seem "too dangerous." Finally, the voices in his head command him to slaughter several complete strangers for no real reason.
Due to obvious insanity, he's acquitted. A few years in a psycho ward under sedation makes him seem harmless. Sooner or later, he gets listed as no longer dangerous and is turned loose.
He's a threat to society and could go off again at any time.
Now contemplate what happens if both are released on a legal technicality 6 months after the trial. Which one would you rather live next door to?
As for our Norwegian killer, I'm thinking the time has come for all countries to consider the death penalty as the standard sentence for mass murderers. If you are liberal enough, you can get all squishy and forgiving over someone who hacks his grandmother to bits with a hatchet, but please let's permanently get rid of these really dangerous ones without regard to any claims regarding sanity.