OSLO, Norway — Police are increasingly certain that mass killer Anders Behring Breivik acted alone, but are leaving no stone unturned in the hunt for collaborators as they try to close one of the bloodiest chapters in Norway's history.
Breivik, 32, killed eight people in a bomb attack in central Oslo last Friday and then shot 68 at an island summer camp for the ruling Labor Party's youth wing.
He has told police he was part of a network in his self-styled "crusade" against Islam and multiculturalism — but Norwegian authorities doubt this.
"So far we have no indication that he has any accomplices or that there are more cells," the head of the Norwegian Police Security Service, Janne Kristiansen, told Reuters on Wednesday. His claim was likely to have been a play for publicity, she said.
Kristiansen said there would be no let-up in hunting Breivik's possible partners, however unlikely, or in police monitoring of extremists.
"As long as there is a tiny chance...we have to investigate it -- that is our main focus," said Kristiansen, who added that Breivik was "too calculated, too focused" to be considered insane.
Norway agreed on Wednesday to review security and the police response to the killings.
"It's important to clarify all aspects of the attacks to learn lessons from what has occurred," Prime Minister Jens Stoltenberg said after parliamentary leaders agreed to appoint an independent commission to review the attack after a period of mourning.
Critics have questioned whether the police acted too slowly to the shooting spree in Utoya, which went on for about 90 minutes before Breivik was arrested, and whether security in the Nordic nation is too lax.
"(Police) organization and capacity will be part of an evaluation,'' Stoltenberg said. He expected the attacks to stimulate political engagement among his compatriots, he said.Story: Police begin to release IDs of Norway massacre victims
Norwegians, unused to violence in a quiet country of 4.8 million, must now struggle with how to improve security without jeopardizing the freedom and openness of their society.
"Our challenge will be to reconcile those two things,'' Stoltenberg said, denying that Norway had been naive. "It is very important to distinguish between naivete and openness."
He said he welcomed a debate about security measures and the police response to the emergency.
Search for international links
Breivik is said to have given varying accounts of his actions, first saying he operated alone and then telling a judge he was part of a wider network.
Norway's domestic intelligence chief said she believed Breivik was a lone operator and contested an assertion by his lawyer that his client was probably insane.
"So far we have no indication that he has any accomplices or that there are more cells,'' Janne Kristiansen told Reuters.
Nonetheless, Kristiansen said police had not ruled out that there could be others involved and that they were in touch with police outside Norway.
"We are working with the other security services in the rest of Europe, in America and the rest of the world,'' she said.
Kristiansen said Breivik's strategy is to spread fear to make sure he is kept in the limelight, partly achieved by saying he has other cells of sympathizers.Story: European police probe Norway attacker's links to right-wing groups
Asked about Breivik's claim of affiliation to a "Knights Templar" group, Kristiansen said it had existed at some point, but that security services have had no knowledge of it for a few years. She declined to disclose any more information.
Meanwhile, a member of Belgian right-wing party Vlaams Belang who received Breivik's manifesto said Breivik sent the 1,500-page document to 250 British email addresses, The Guardian newspaper reported.
"I think the U.K. was the biggest group [of recipients]," Tangur Veys said. "There were people from Italy, France, Germany ... but the U.K. was the biggest number."
The Guardian cited reports that the domestic extremism unit at the Britain's Scotland Yard, which is investigating Breivik's alleged links to the U.K., has a list of British-based email addresses. The Metropolitan Police refused to confirm the report, The Guardian said.
Separately on Wednesday, police in Germany raided 21 homes and properties linked to suspected right-wing extremists, the prosecutor's office in the state capital Stuttgart said.
The investigation, which was launched in March, was not linked to Norway's attacks, according to the office.
Some 140 police officers took part in the raid in Baden-Wuerttemberg state, seizing weapons, ammunition, drugs and computers from 18 people involved with a group known as "Standarte Wuerrttemberg," which aims to expel all foreigners from Germany.Story: Unsettling wariness in Norway, where cops are rarely armed
Insane, calculated or both?
On Tuesday night police destroyed an explosives cache found at a farm rented by Breivik, some 100 miles north of Oslo. They believe he made his bomb using fertilizer which he had bought under the guise of a farmer.
They detonated another cache on Wednesday.
Breivik's lawyer, Geir Lippestad, said his client was probably insane, but it was too early to say if the loner and computer game enthusiast would plead insanity at his trial.
Breivik has confessed to his actions, but denied guilt, saying he was part of a network with two cells in Norway and more abroad that was fighting to save European "Christendom" from the spread of Islam and multi-culturalism.Breivik, birthers: What they have in common
Kristiansen said she did not believe Breivik was insane, or that he would plead insanity at his trial.
"He is too calculated, too focused. He is not going to plead insanity,'' she said. "He wants to be seen as the savior of the world, and you can't be insane to be that."
Breivik, 32, has asked that non-Norwegian psychiatrists assess him, police lawyer Paal-Fredrik Hjort Kraby said.
Breivik, who was remanded in custody for eight weeks on Monday, has been charged under the terrorism act, which carries a maximum penalty of 21 years in jail, but the authorities are considering whether to charge him with crimes against humanity.
Stoltenberg said that Norway had a system allowing sentences to be extended if there were a risk of new crimes.
Below the radar
Both Norwegian and international media have questioned how it has been possible for Breivik to stay below the police radar for so long, having planned the attack for many years.
"This person's strategy is to be below the radar,'' Kristiansen said, when asked how he had avoided being noticed.
"He has done everything on his own in a way that will make the police suspicious of nothing. He has not broken the law. He has had a strategy, and sorry to say he has succeeded in that strategy."
Kristiansen said the security services had warned in their threat assessment earlier this year that right-wing extremism is on the rise in Europe and that there were "some in Norway" but that right and left extremist groups will not pose a "serious threat" to Norway in 2011.
Justice Minister Knut Storberget deflected criticism that police reacted too slowly to the shootings, hailing their work after the attacks as "fantastic."
Many Norwegians seem to agree the police do not deserve reproach for their response. At a rally of more than 200,000 in Oslo on Monday night, people applauded rescue workers.
Trying to move forward
Jittery Norwegians sought to restore some normality five days after the bloodshed, as police reopened some streets around the blast site in Oslo and shops gradually reopened for business.
But two false alarms kept people on edge. A security alert forced the evacuation of Oslo's central station on Wednesday,after a suspicious suitcase was found on a bus. Police said later it was harmless.
In another false alarm, police retracted a search alert for a man who they suspected of sympathizing with Breivik, saying in fact they wanted to detain a mentally ill man with no link to
In a symbolic effort to promote normalcy, cabinet minister Rigmor Aaserud returned to her office in Oslo's government district where Breivik detonated the bomb on Friday. Her office, in a government complex, was little damaged.
The bomb blew a hole in Stoltenberg's office. For now, he will work from the defense ministry in a different area of Oslo and cabinet meetings will be held in a medieval fort near the waterfront. It is not clear whether the 17-storey prime ministry building will be rebuilt or torn down.
In Stoltenberg's building, which took the brunt of the car bomb, curtains still flapped from broken windows.Slideshow: Norway mourns after massacre (on this page)
The prime minister, who knew some of the victims, has caught the national mood, urging his compatriots in a voice often cracking with emotion to unite around democratic values.
"We are even more aware of any dangers now than before the attack. But in general Norwegians want ... to defend themselves against violence by showing they are not afraid of violence."
Karl Johans Gate, is showered with flowers as Norwegians pay their respects to victims while nearby vendors gradually reopen for business.
On Tuesday, workers at a corner store about 150 yards from the blast painted the plywood boards put up in place of blown-out windows. Others were busy cleaning up inside.
"Fixing the glass (windows) will take a week or two and the wood looks better painted," said deputy store manager Aykan Bastas. "We will fix it up nicely, just like before."
Reuters contributed to this report.