Norwegian mass killer Anders Behring Breivik speaks to one of his lawyers Vibeke Hein Baera (R) as he arrives to hear the verdict in his trial at a courtroom in Oslo August 24, 2012.[Agencies]

Although his victims were mostly teenagers, with some as young as 14, he rejected being called a child murderer, arguing that his victims were brainwashed "cultural Marxists" whose political activism would adulterate pure Norwegian blood.

He stalked his victims dressed as a policeman, tricking them into thinking he was the help sent from the shore, then shot them from close range before finishing them with a shot to the head.

"I stand by what I have done and I would still do it again." he said during his court testimony.

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One team of court appointed psychiatrists concluded he was psychotic while another came to the opposing conclusion. To make the ruling more difficult, several other experts who testified described a slew of mental conditions Breivik probably suffered.

Still, polls showed that around 70 percent of Norway's public thought such a complex attack could not have been carried out by a madman and Breivik had to bear responsibility.

"The most important thing for me is not weather he is sent to a mental hospital or jail, it's just that he remains off the streets (and) he is never let out," Vegard Groslie Wennesland, a survivor of the attack said before the verdict.

Breivik has said he would accept a sane verdict, but derided a jail term as "pathetic", and said acquittal or execution were the only reasonable outcomes.

A commission investigating the attack earlier this month concluded that all of part of it could have been prevented and intelligence, police and government blunders likely cost lives.