OSLO, May 25 (Reuters) - Norwegian mass killer Anders Behring Breivik first requested a band aid for a cut finger when police arrested him, then posed like a bodybuilder after he was stripped and police took his picture, witnesses told a court on Friday.

Breivik killed 77 people on July 22, first detonating a car bomb outside government headquarters and killing eight, then gunning down 69 people, mostly teenagers, at the ruling Labour Party's summer camp on Utoeya Island.

He then surrendered, with blood loss from a cut finger seeming his main concern.

"I said you get no band aid from me," police superintendent Havard Gaasbakk told court on Friday. "Look around - dead and wounded people are lying everywhere."

Breivik was then led away for questioning and police stripped him of his fake police uniform, which he used to deceive people to think he was there to stop the killer who had been hunting people down.

"He first refused to let himself be photographed, but changed behaviour when he was stripped to his underwear," said a special unit officer, who the court said should not be identified by name. "It almost seemed like he wanted to pose, doing poses like a bodybuilder."

Shortly before, Breivik had moved methodically through the island, luring people from their hiding and shooting them in the head.

Adrian Pracon, who was spared because Breivik thought he looked like a right-wing supporter, said the killer shouted "I will kill you all" and "you shall die" as took down his victims.

The court's main task in the 10-week trial is to decide whether Breivik was sane and whether he should be sent to jail or a psychiatric institution.

One court-appointed team of psychiatrists concluded he was psychotic, but a second team came to the opposite conclusion. The five judges hearing the case will take a final decision on his sanity at the end of the trial, expected in late June.

If deemed sane, Breivik faces a 21-year jail sentence which could be indefinitely extended for as long as he is considered dangerous.

Breivik has said he should either be executed or acquitted, calling the prospect of a prison sentence "pathetic". If he were to be declared insane, he has said, that would be "worse than death". (Reporting by Balazs Koranyi; Editing by Mark Heinrich)

The Charges
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Anders Behring Breivik, a right-wing extremist who confessed to a bombing and mass shooting that killed 77 people on July 22, 2011, arrives for a detention hearing at a court in Oslo, Norway, Monday, Feb. 6, 2012. (AP Photo/Heiko Junge, Scanpix Norway)

Breivik is charged with terrorism and premeditated murder for a bombing in Oslo's government district, killing eight, and a shooting attack at a political youth camp, killing 69. He admits to the attacks but rejects criminal guilt. If convicted he would face a maximum sentence of 21 years in prison, though sentences can be extended if a criminal is considered a menace to society. If declared insane by the court, he would be committed to psychiatric care. Both sides can appeal the ruling to a higher court.