Psychiatrists in Norway say they believe the man who killed 77 people in Oslo and on the island of Utoeya in July was insane.
They have concluded that Anders Behring Breivik is a paranoid schizophrenic who believes he was chosen to save the Norwegian people and to decide who should live or die.
Breivik admits carrying out the attacks on 22 July, but has pleaded not guilty.
Breivik, 32, is due to stand trial on 16 April. But the BBC reports it is likely he willl be sent into psychiatric care rather than prison.
Prosecutors said on Tuesday that two psychiatrists who interviewed him on 13 occasions concluded that he lived in his own delusional universe where all his thoughts and acts are guided by his delusions.
On 22 July, Breivik disguised himself as a police officer to plant a car bomb that exploded close to government offices in the capital Oslo, killing eight people.
Still in uniform, he then drove to the island of Utoeya, where a summer youth camp of the governing Labour Party was being held.
In a shooting spree that lasted more than an hour, he killed 69 people there - mostly teenagers.
Another 151 were wounded in total that day.