Anders Behring Breivik is to appear in court on Monday, almost nine months after he admitted killing 77 people by detonating a bomb in the centre of Oslo and opening fire on youngsters attending a summer camp on Utoya island.
The 33-year-old is charged with terrorism, but he intends to plead not guilty, arguing the attacks were a political act designed to prevent what he described as an Islamic invasion of Norway.
His defence lawyer, Vibeke Hein Baera, has told Sky News that part of their strategy is to call a series of extremists as witnesses, to question an initial psychiatric report that deemed Breivik to be criminally insane.
A second report disputed those findings and a panel of two professional and three lay judges will have to decide whether Breivik should be sent for treatment at a psychiatric hospital or jailed for life.
The 10-week trial, which is being held in a specially-built courtroom that includes sheets of toughened glass behind the defendant, will also hear from eyewitnesses, survivors and forensic experts.
After entering his plea, Breivik will take the stand again on Tuesday.
He is expected to say he wishes he had "gone further", but cameras relaying the trial to over a dozen satellite courts around Norway and television stations around the world will be switched off during his evidence to deny him a platform for his extremist views.
The prosecution will tell the court the killings were pre-meditated murder.
They will say he bought a fake police uniform and badges in the Czech Republic in 2010 before renting a farm 90 miles from Oslo where he wrote a 1,500 page manifesto and started to assemble a bomb from fertilisers, diesel and chemicals.
Both sides agree that on July 22, 2011, he drove the device into the government quarter of the capital just after 3.15pm, parked it in front of the building which housed the Prime Minister's office, lit a seven-minute fuse, then walked to a getaway car.
Eight people were killed in the devastating explosion and more than 200 were injured. As survivors stumbled through the rubble, Breivik was already on his way to Utoya island, where the AUF Labour Party was holding its annual summer camp.
On his way, he heard on the radio that the government building he had hoped to topple was still standing.
The court will hear how he later told police he knew he had to move to 'plan B' to gain more publicity for his cause.
After convincing AUF organisers on the mainland that he was a policeman sent to secure the island after the bomb blast in Oslo, he made the short trip over the water.
Then the massacre began.
For over an hour he aimed, fired and reloaded as terrified youngsters ran for cover and others fell with fatal gunshot wounds. In all, 186 bullet casings were found on the island.
Most of the victims died from shots to the head. Many had been shot several times.
He surrendered after officers finally arrived on the island, having called police to say that his "mission" had been "accomplished".
The police force has since apologised for errors in its response and the speed at which they reached Utoya.