After nearly 10 weeks of grueling testimony of one of the worst peacetime massacres in modern history, it's time for prosecutors to decide their position on whether they think confessed mass killer Anders Behring Breivik is insane or not.

"The decision has been made," prosecutor Svein Holden told reporters Wednesday. But prosecutors declined to say what that was a day before closing arguments in a trial that has captivated Norway since the middle of April.

Ultimately, judges will decide Breivik's mental state when they hand down a verdict in July or August.

Breivik, a self-described anti-Muslim militant, has admitted he carried out the bombing and shooting rampage that left 77 people dead on July 22, so guilt is not an issue. The main issue to determine is whether to send the 33-year-old Norwegian to a prison or a mental institution.

Weeks of fractious testimony from mental health experts suggest it's a complicated decision, and Breivik's behavior in court has not made it any easier.

At the close of Wednesday's Oslo District Court hearing, in which experts described the psychological aftershocks suffered by those who survived the attacks and the relatives of victims, Breivik complained that not enough attention was given to his own suffering at seeing Norway become a multicultural society.

"This case is about Norway's future, and Europe's future, and these were themes they should have addressed," he said, adding that it was "a traumatic experience ... to be stigmatized as a narrow-minded Islamophobe and right-wing extremist."

Breivik claims Norway and Europe are being colonized by Muslims, who make up about 2 percent of Norway's population. He has said he selected his targets _ a government high-rise and a summer camp for the governing Labor Party's youth organization _ to strike against the political forces he claims betrayed the country with liberal immigration policies.

But court-appointed psychiatrists disagree on whether his actions were prompted by an extreme political ideology, or by the delusions of a psychotic mind.

Prosecutors will present their views Thursday, with the defense given a chance to comment in its closing arguments Friday. Defense is likely to reiterate Breivik's view that he is sane, and that the psychiatric dimension of the trial is detracting from his political message.

The five-judge panel then has at least a month to deliberate before it hands down a ruling.

If deemed psychotic, Breivik would be sent to compulsory psychiatric care. If found sane, he would most likely receive a 21-year prison sentence _ the maximum under Norwegian law.

Breivik could, however, be held for longer if considered a menace to society.