Anders Behring Breivik, the 33-year-old who has confessed to murdering 77 people in two attacks in Norway, has been charged with committing acts of terror.
Breivik, whose attacks shocked Norway, harboured radical right-wing views and had railed against what he saw as a Marxist Islamic takeover of Europe.
On the day of the massacre, Behring Breivik published a 1500-page tract on the internet in which he lays out his Islamophobic and anti-Marxist ideology developed over the past nine years - and the moment in 2009 he decided to put words into action.
Presenting himself as a Crusader, he explains how he hid from his friends and family to prevent his plot being exposed. And his secret appears to have stayed just that.
Behring Breivik says himself that he had an unremarkable childhood, with a diplomat father and a nurse mother who divorced when he was just one year old.
"I have had a privileged upbringing with responsible and intelligent people around me," he wrote in his tract.
Raised by his mother in a middle class family, he said he never had financial problems and has only one gripe: "I had way too much freedom, though, if anything."
"When he was younger, he was an ordinary boy but not very communicative.
He was not interested in politics at the time," his father Anders, with whom he lost contact aged 15, told Norwegian newspaper VG on Sunday.
In 1999 he joined the populist right-wing Progress Party and was active with the party's local youth branch.
He ended his membership in 2006, writing later on an internet forum that he felt the party was too open to "multicultural demands" and "the suicidal ideas of humanism".
"Those who knew him when he was a member of the organisation say that he was a fairly shy boy who rarely took part in discussions," the Progress Party said on Saturday.
While his criticism of Islam, multiculturalism and Marxism are all over the internet - where he was very active - Behring Breivik considered himself to be "a laid back type and quite tolerant on most issues".
"Due to the fact that I have been exposed to decades of multicultural indoctrination I feel a need to emphasise that I am not in fact a racist and never have been," he wrote.
"Being a skinhead was never an option for me. Their dress codes and taste of music was unappealing and I thought they were too extreme," he wrote, adding that he had "dozens of non-Norwegian friends during my younger years".
On his Facebook profile, Behring Breivik describes himself as conservative, Christian and interested in hunting and video games such as World of Warcraft and Modern Warfare 2.
He had little or no income in 2009 and previous years, according to his tax declaration - public information in Norway - and bought a small piece of agricultural land earlier this year.
That allowed him in May to buy, without raising suspicions, six tonnes of fertiliser and chemicals, which he apparently used to make the explosives used against government buildings on Friday, killing seven.
He also joined a shooting club, which enabled him to get the permit to buy firearms, including an assault rifle believed to have been used as he shot dead scores of young Labour Party members on the island of Utoya, near Oslo.
