Right-wing fanatic Anders Breivik, who killed 77 people in bombing and shooting attacks in Norway, sees himself as a 21st century crusader battling against Islam in Europe.
The 33-year-old has confessed to the attacks but denies criminal guilt, saying he acted to stop colonisation by Muslims, which was happening because of the immigration policies of those in power.
A psychiatric assessment found him to be psychotic and suffering from paranoid schizophrenia, but he insists he is sane - a view supported by a second assessment ordered by the Oslo District Court.
Judges at his trial will decide whether he is insane or not.
Breivik attempted to justify his views in a 1,500-page manifesto published on the internet before the atrocities.
He claimed to be part of a secret organisation modelled on the medieval Christian military order the Knights Templar.
He said it aimed to purge Europe of Muslim influence in a revolution that would target what he called "cultural Marxists" in the initial phase.
The document spelt out Breivik's extreme nationalist philosophy as well as his methods. It described how he bought guns, tons of fertiliser and other bomb components, hid collections of weapons and evaded police suspicion in the run-up to the attacks.
Police have not been able to substantiate his claims of being in a group and believe he acted alone.
It was widely reported in the wake of the attacks last July that Breivik had made postings on British nationalist websites.
However, Norwegian authorities said there was no evidence of links between Breivik and the English far-right, adding that there were no indications he had been part of a broader movement.