In his early 20s, Breivik writes, he spent a year working alongside a mentor who schooled him in the ways of business and management. The man calls that a bizarre exaggeration, noting that the only thing he taught Breivik was how to record corporate minutes.
Those conflicts between Breivik's account and reality hint at a long thread of delusion winding throughout the 1,518-page manifesto he emailed to hundreds of people hours before he set out on a murderous rampage just over a week ago.
But some questions are raised by the fragments of Breivik's story that those who knew him say are closest to the truth.
The killer describes teen years infatuated with hip-hop, sneaking out at night in baggy jeans and hooded sweatshirts to spray-paint buildings around the capital with graffiti under the tag name "Morg." Then, Breivik writes, he decided to reject that life and turn himself into a selfless crusader bent on rescuing society from itself.
Former friends confirm the tales of schoolboy troublemaking. But they also recall Breivik as the one who repeatedly stepped forward to stop the most popular students from teasing or bullying his classmates. He was a singular boy, reluctant to reveal his own thoughts, but one who would willingly sit for hours in the garden outside a friend's house listening to her talk about herself.
"If someone were mean to me he would always stand up for me ... and I think in his head he was just trying to protect us," recalls Caroline Fronth, a friend of Breivik's between seventh and ninth grade. "He was struggling to find his path and we all did in our class ... and that's what's terrible here, because he found his way."
"But it was the wrong way. It was a monstrous way."
According to Breivik's manifesto, he plotted for nearly nine years to carry out his attack. Investigators say that they have found no signs of a larger conspiracy and that he does not appear to have shared his plans with anyone.
Then, on July 22, he parked a van loaded with a bomb made from fertilizer outside government offices in central Oslo. It exploded, killing eight. Less than two hours later, Breivik walked into a youth political camp on an island outside the city, dressed as a policeman and armed with a handgun and a modified semiautomatic rifle, and embarked on a rampage, shooting his victims twice.
Breivik, 32, claims he carried out the attacks as part of a network of modern-day crusaders to launch a revolution against a Europe spoiled by Muslim immigration, and that there are other cells ready to strike.
But investigators say they have found no signs of a larger conspiracy.
In the days since the attacks, Norwegians -- especially those who knew Breivik -- have puzzled over his motives and his mindset, trying to reconcile the deeds with a life that, outwardly at least, seemed quite ordinary.
What snapped inside Breivik that so warped his perception of self and society he would slaughter 77 of his countrymen in the name of saving them? Retracing his story hints at a set of possible answers.
In the manifesto, Breivik waxes fondly for the Europe of old, full of fathers who dutifully went off to work every morning and mothers who stayed at home and knew their place. The reality of his own life was quite different. Both of his parents worked full-time and they divorced when he was one. His father remarried and, as a Norwegian consular official, lived mostly outside the country.
His mother, a nurse who also remarried, won custody, raising her son in a first-floor apartment on the west side of Oslo, generally considered the most fashionable and affluent part of the city. But Fronth -- who along with Breivik was part of a group of five friends who spent hours together -- says Breivik chafed at the differences between himself and classmates from families with more money.
The red brick apartment building, where his mother Wenche Behring still lives, fronts a busy street that has been redeveloped with office buildings in recent years. But at the time, the street was scruffy compared to nearby neighborhoods and decidedly working class, Fronth says. It contrasted sharply with the blocks of neatly tended homes with red tile roofs, sitting behind walls Breivik passed on the walk to Ris junior high school.
"He didn't like it," Fronth says. "He wanted to be one of those with a big house with a garden who had money."
At school, Breivik did not have many friends, but he was hardly anti-social, said Michael Tomala, a former classmate. Breivik spent hours lifting weights, often with a friend, Arsalan Ahmad Sohail, the son of a Pakistani immigrant family, leaving the pair of boys bigger than many of their classmates. Sohail's father and wife said this week that he would not comment on his relationship with Breivik.
Tomala recalls that rather than pushing his weight around, Breivik often served as classroom peacemaker.
"Not only once, but a few times, he would come in between conflicts ... He would actually stop a fight and say, look, leave him alone, he hasn't done anything," Tomala said. "I remember him as having a grown-up way of doing things."
Tomala says that attitude extended to conversations with Breivik. He recalled one during which Breivik encouraged him to stand up to classmates who were giving him a hard time for devoting so much energy to training for the track and field team.
Tomala and Fronth say that Breivik and other boys in class began sneaking out at night to paint graffiti. Fronth, who recalls being asked to keep watch while the boys wielded the paint cans, says Breivik was very impressionable, trying to prove his worth by doing what the most popular classmates did.
But he was also a dutiful friend, a relationship aided by the fact that Breivik did not seem to have much interest in girls.
"We were just friends, talking about everything and nothing, just hanging out," says Fronth, who today is a nurse.
Sitting in her family's garden, Breivik listened patiently as Fronth talked. But he rarely voiced his own feelings, beyond his apparent irritation at classmates' infatuation with social status.
"It was hard for us to get into his head," Fronth said. "I think he was pretty intelligent, but he didn't show emotion. He didn't smile much or ever cry. He was just there all the time. It was really hard to figure out who he was."
Breivik had been visiting his father, Jens, and new wife regularly over the years. But when he was about 15, all contact ceased. Fronth says she could tell that bothered her friend. In his manifesto, Breivik writes that he didn't have "any negative experiences" in his childhood. But he suggests that his father was upset with his graffiti sprees.
"He wasn't happy about that relationship since he didn't have any contacts," said Tove Overmo, Jens Breivik's second wife, who stayed in touch with her husband's son even after they were divorced. "I think he had a wish to have contact with his father."
Breivik writes that starting when he was 15, gangs of Muslim teens increasingly threatened him and his classmates and that he confronted them, a contention that is hard to verify, but that he says was formative to his anti-Muslim views.
The manifesto details eight run-ins with Muslims, including one when Breivik was 17.
"I was at a party on Tasen when we heard they had just beaten on of my friend's younger brothers. We went to chase them away from the neighborhood. They had weapons, we had weapons. I was hit with a billiard pool in the head. Result of the fight: we made a deal with them. They promised they would never return and harass the Tasen youngsters again," he writes.
After graduating from high school, Breivik worked in a series of jobs, including at a call center and a bank. But parts of the account in his manifesto appear to vastly inflate his accomplishments and experience. In 2000 and 2001, he writes of spending a year working alongside "mentor" Richard Steenfeldt Berg as a consultant hired by his company, Hypertec AS. Berg coached him in management, administration and business development, Breivik writes.
But Berg, who says the pair knew each other for just a few months and that contact with Breivik consisted of a "limited number of visits" to his office, sharply disputes the characterization of the relationship.
"Yes, I met this monster 11 years ago. No, I did not coach him in any subjects, except for some advice on writing corporate minutes protocol, which he requested fervently," Berg says in an open letter he posted this week on his Facebook page. "No, I have never acted as, nor accepted the role of, any kind of 'mentor' for him."
Berg, who says Breivik struck him as "deeply disturbed," could not be reached for additional comment.
Two years later, Breivik writes, he was nominated by the Progress Party to run for a seat on the Oslo city council and "came relatively close to being elected." But according to the manifesto, those aspirations were stonewalled by "my rival" Joran Kallmyr, who was chairman of the party's youth wing and is now a vice mayor of Oslo.
"I barely remember him," Kallmyr said in an interview. Breivik attended just five or six meetings of the youth party, his presence unremarkable except for the fact that he was the only one wearing a tie, Kallmyr said.
"I think I talked to him. I remember a conversation about his business. I remember there was nothing special about him that could lead to something like this," Kallmyr said.
In 2002, Breivik writes, he started the first of a few business ventures, a software outsourcing company. At about the same time, he says he began laying plans for radical action, concluding that working through traditional political channels would be fruitless.
Three years later, he writes, the company had grown into a successor firm that employed seven people, but he was secretly using it as a front, "with the purpose of financing resistance/liberation related military operations."
Breivik said friends respected him because the business had done so well, making him 4 million kroner ($739,000) by the time he was 26, in 2005.
"I believe less than five self-made individuals have accomplished more at that young age in my country," he wrote.
Norwegian tax records show Breivik earned the equivalent of just $969 dollars in 2006 and 2007, even as his reported wealth rose to as much as $117,000.
But he shut down the company in 2007 when its fortunes turned during a recession, according to the manifesto.
The auditor of Breivik's company withdrew its services in August 2007 for a reason it will not specify and the business was dissolved the following January, as required by Norwegian law.
In May 2009, government records show, Breivik started his final venture, a sole proprietorship called Breivik Geofarm that listed its business as "growing of vegetables, melons, roots and tubers." The company's name is still printed below Breivik's mother's name on the bell outside her apartment building's ivy-draped doorway.
By then, according to his manifesto, Breivik's plot was gaining speed.
In June of 2010, he renewed a membership in the Oslo Pistol Club, a shooter's practice range that sits at the end of a gravel road in the woods outside the city. The club said in a note posted on its website this week that Breivik had previously been a member from 2005 to 2007. Gun ownership is tightly restricted in Norway, but relatively common, reflecting the popularity of hunting.
"The club, like other similar clubs, has no role in evaluating potential members' suitability as weapons owners beyond what we observe on the range," the club said in its note, which expressed the group's grief for the victims. Breivik participated in 13 organized training sessions and one shooting competition since rejoining last year, the club said.
According to his manifesto and to investigators, Breivik used the Geofarm business as a front earlier this year to buy the fertilizer and other chemicals required to make the bomb. He used two guns during his rampage on Utoya island, both of which police say he bought legally.
But Breivik wrote that he had said nothing to friends and family about his views or intentions, telling them only that he was working on new business ventures, including one that involved farming, and that he was nearing completion of a book he had been researching for many years.
In March, he visited his former stepmother, Overmo -- retired after a career with Norway's foreign service -- at her home south of Oslo.
This week, Overmo went over and over the details of the visit in her mind, searching in retrospect for a sign of what her stepson was thinking, any hint of the secrets he was hiding.
"If I'd had some kind of suspicion, some kind of idea that something was not right with him, it would have been easier I think," she said. "He left saying ... see you again soon or something like that -- something very normal."
But that's not the way Breivik remembered the visit with Overmo.
"Although I care for her a great deal, I wouldn't hold it against the (Knights Templar) if she was executed during an attack against UDI," Norway's immigration agency, Breivik wrote in his manifesto.
Overmo said her only experience at UDI was three months of training before a new consular assignment. But Breivik calls her a director of the agency.
"Regime sub-leaders such as her are on auto pilot, though, and partly disconnected from reality and thus partly unaware of their own war crimes," he wrote in the manifesto just before the visit -- and four months before he launched his attack.
"So when I meet her I will probably just end up talking about the usual social BS to prevent raising any red flags."
Associated Press Writers Ian MacDougall and Bjoern H. Amland in Oslo contributed to this story.