Explosives found at a farm leased by Anders Behring Breivik, the sole suspect in Friday's killings in Norway, have been safely detonated in a controlled explosion about 160km north of Oslo by the Norwegian police.
Police believe that Breivik, 32, made his bomb using fertiliser which he had bought under the cover that he was a farmer.
Tueday's detonation came as Breivik's lawyer, Geir Lippestad, said that he was probably insane, and was on drugs while he carried out his attacks that killed 68 in Utoeya island and eight in Oslo.
Lippestad said it was too early to say if his client would plead insanity at his trial, even though he thought Breivik, a computer-games enthusiast and a loner, was probably a madman.
"This whole case indicated that he is insane," Lippestad said of Breivik, who has confessed to "atrocious but necessary" actions, but denies he is a criminal.
Lippestad said Breivik had stated he belonged to a radical network that had two cells in Norway and more abroad.
'Calculating and evil'
But police believe Breivik probably acted alone in staging his assaults, which have united Norwegians in revulsion.
"I can tell you on a general basis that so far we don't have any evidence of the cells, neither in Norway or in Britain," Janne Kristiansen, head of the PST security police, told the BBC.
Jonah Hull reports on the growing anti-immigration sentiments in Norway
Breivik's online manifesto referred to a secret meeting in London in 2002 to found a 'Knights Templar' group to drive Islam out of Europe.
The BBC quoted Kristiansen as saying she rejected the theory that Breivik was insane, calling him calculating and evil.
Meanwhile, Rigmor Aasrud, Norwegian administration and Church affairs minister, will make a symbolic return on Wednesday to her office after the bomb blew a hole through the prime minister's office and badly damaged other buildings.
For the time being, Jens Stoltenberg, the prime minister, will work from the defence ministry which is in another part of the city, and cabinet meetings will be held in a mediaeval fort near the Oslo waterfront.
It is not clear whether the prime minister's 17-storey building will be rebuilt or torn down.
With Norway been struggling to come to terms with what happened, Knut Storberget, the justice minister, deflected criticism that police reacted slowly to the shootings, hailing their work after the attacks as "fantastic".
An armed SWAT team took more than an hour to reach Utoeya island, about 45kms from Oslo, where Breivik was shooting youngsters at a Labour Party youth camp.
Storberget also denied police had ignored threats posed by right-wing zealots in Norway, saying: "I reject suggestions that we have not had the far-right under the microscope."
Many Norwegians seem to agree that the police do not deserve opprobrium for their response. At a march of more than 100,000 in Oslo on Monday night, people applauded rescue workers.
Police defended themselves from suggestions that some alarm bells should have rung about Breivik. The PST security police say Breivik's name appeared only once, on an Interpol list of 50 to 60 Norwegians, after he paid 120 crowns ($22) to a Polish chemicals firm on a watch list. They found no reason to react.
Researchers doubt Breivik's claim that he is part of a wider far-right network of anti-Islam "crusaders", seeing it as bragging by a psychopathic fantasist who has written that exaggeration is a way to sow confusion among investigators.
Police have reopened some streets around the blast site and Oslo's main thoroughfare, Karl Johans Gate, is showered with flowers as Norwegians pay their respects to victims, while nearby vendors gradually reopen for business.