A 1,500-page manifesto published online and reportedly posted on the day of the attack ranted against Muslim immigration to Europe and vowed revenge on "indigenous Europeans," whom he accused of betraying their heritage. It added that they would be punished for their "treasonous acts."
Police, who are poring over the manifesto, have not confirmed that their 32-year-old Norwegian suspect Anders Behring Breivik wrote the document, but his lawyer referred to it and said Breivik had been working on the document entitled, "2083 - A European Declaration of Independence," for years.
Part of it was taken almost word for word from the writings of the Unabomber.
A 12-minute video clip posted on YouTube with the same title as the manifesto featured symbolic imagery of the Knights Templar and crusader kings as well as slides suggesting Europe is being overrun by Muslims. Police could not confirm that Breivik had posted the video, which also featured photographs of him dressed in a formal military uniform and in a wet suit pointing an assault rifle.
"He wanted a change in society and, from his perspective, he needed to force through a revolution," Geir Lippestad, his lawyer, told public broadcaster NRK. "He wished to attack society and the structure of society."
The document detailed plans to obtain firearms and explosives and even appeared to describe a test explosion: "BOOM! The detonation was successful!!!" It ends with a note dated 12:51 p.m. on July 22: "I believe this will be my last entry."
That day, a bomb killed seven people in downtown Oslo and, hours later, a gunman opened fire on dozens of young people at a retreat on Utoya island.
Witnesses at the island youth retreat described the way Breivik lured them close by saying he was a police officer before raising his weapons. People hid and fled into the water to escape the rampage; some played dead.
Police said Sunday that the death toll in the shooting rose to 86.
That brings the number of victims to 93, with more than 90 wounded. There are still people missing at both scenes. Rescuers on boats are continuing to search for bodies in the water, and body parts remain inside the building, which housed the prime minister's office.
Police and his lawyer have said that Breivik confessed to the twin attacks, but denied criminal responsibility for a day that shook peaceful Norway to its core and was the deadliest ever in peacetime. Breivik has been charged with terrorism and will be arraigned Monday.
Norway mourned the victims of the bombing attack and shooting spree. Norway's King Harald V and his wife Queen Sonja and Prime Minister Jens Stoltenberg were among those who gathered at an Oslo cathedral for a memorial service Sunday.
Gun violence is rare in Norway, where the average policeman patrolling in the streets doesn't carry a firearm. Reports that the assailant was motivated by political ideology was shocking to many Norwegians, who pride themselves on the openness of their society.
Suspect's sister may live in Southern California
In his manifesto, Breivik makes reference to his sister, saying she lives in West Los Angeles.
On Sunday night, no one answered the door at the apartment where she is believed to live. Neighbors posted signs on their door asking not to be disturbed.
Breivik talks about being invited to visit his sister.
"My sister Elisabeth lives in Los Angeles btw and has chosen a life where…you guess it…the acquisition of wealth is the driving force in her life. Well, this is not entirely true," he wrote. "She only wants financial security to live a life without worry and to be able to do what she wants when she wants.
"I used to be just like that so I know where she and millions of other Europeans are coming from."
Norwegian-Americans in L.A. shocked by attack
Norwegian-Americans in Los Angeles shared their thoughts on the double attack in Norway.
In San Pedro where dozens of Norwegians gathered for church Sunday morning, many were struggling to come to terms with the deadly rampage.
"I was just there in Norway walking the same streets that I saw live Sunday from Norway where the bombings took place," Beth Thomassen said. "That was sort of strange, a very strange feeling."
Bjoern Olsen said he has been in contact with friends who were on the island when the violence began. Some barely got away.
"I was concerned he was there and it was confirmed to me that he was actually there when it happened, but he was lucky and he got away in a boat," Olsen said. "Another friend of mine she had to swim in order to get safe home."
The Associated Press contributed to this report.