The Norwegian man suspected of shooting at least 85 people on an island in Norway, and killing seven more after exploding a bomb in central Oslo, has been provisionally charged with two acts of terrorism.
The man, named as 32-year-old Anders Breivik by Norwegian media, is said to harbour right-wing and anti-Muslim views. Police said he is a "fundamentalist Christian".
Hours after Breivik was apprehended details began to emerge about his life and political ideas.
A Facebook account in Breivik's name, which has since been deleted, lists his interests as Christianity, conservative politics, body-building and freemasonry. Pictures posted to the site show him to be a blond, blue-eyed man.
A Twitter account in Breivik's name was also set up recently, to which one single message was posted: "One person with a belief is equal to the force of 100,000 who have only interests."
It has not been confirmed that either account is Breivik's own or that of an impostor.
Police chief Sveinung Sponheim told the Norwegian broadcaster NRK that those posts and others on forums and message boards made in his name "suggest that he has some political traits directed toward the right, and anti-Muslim views" but did not confirm that was the motivation for the attack itself.
Breivik is believed to have grown up in Oslo and attended a nearby school of management. He turned to right-wing extremism in his twenties according to the newspaper Verdens Gang.
Local media in Norway reported that he established a company called Breivik Geofarm, which enabled him to buy large amounts of fertiliser, which can be used in bomb-making, over a two-year period.
According to one farm supply chain company, Breivik bought six tonnes of the fertiliser as recently as May 4.
Breivik had a license to carry weapons, Norwegian media also reported. Police are still searching a flat and a farmhouse owned by Breivik in an Oslo suburb.
It is suspected that Breivik unloaded automatic weapons and handguns on attendees of a youth Labour party camp on the island of Utoya, about 30 kilometres from the capital. He was dressed as a policeman. At least 84 people are now known to have been killed on the island.
The attack came just hours after a huge explosion tore apart a government building in the Norwegian capital, killing seven and injuring many more.
The two attacks represent the worst combined day of violence in Western Europe since the 2004 bombings in Madrid that killed 191 people.
Police director Oystein Maeland said:
"It's taken time to search the area. What we know now is that we can say that there are at least 80 killed at Utoya," Mr Maeland said. "It goes without saying that this gives dimensions to this incident that are exceptional."