Anders Behring Breivik, who killed 77 people in Norway last July, should be locked up in a psychiatric ward instead of prison, the prosecution said Thursday, arguing his sanity had not been proven beyond reasonable doubt.

If the Oslo court judges instead conclude that the confessed killer is criminally sane, prosecutor Svein Holden asked that they sentence Breivik to Norway's maximum penalty of 21 years in prison, which can be extended for as long as he is considered a danger to society.