Oslo, Norway (CNN) -- The man behind a pair of bloody terror attacks in Norway is set to appear in court Monday, his first such appearance since authorities say he killed at least 93 people by setting off an explosion and gunning down people at a youth camp.
Police have not identified the suspect, but local television and newspaper reports say the man in custody is Anders Behring Breivik.
Attorney Geir Lippestad, who claimed to represent the 32-year-old Breivik, told Norwegian TV2 late Saturday that his client "is ready to explain himself" in court. The suspect feels the terrorist attacks were "horrible," but "in his head (they) were necessary," Lippestad said.
The 32-year-old Norwegian has said that he acted alone and has not pleaded guilty, acting National Police Chief Sveinung Sponheim said Sunday. But authorities have not ruled out that others may have been involved or helped him along the way.
The investigation continues as the Scandinavian nation continues to wrestle with the attacks' aftermath, with an ashen-faced and openly weeping King Harald V leading the nation in mourning Sunday. Memorial shrines with flowers and candles dotted Oslo's streets, and Norwegians gathered at a cathedral in the capital to mourn the victims of the attacks.
"Soon, names and photographs will be released. The enormity of the evilness will surface in all its horror, and that will be a new test for us all," Prime Minister Jens Stoltenberg said at a church service Sunday billed as a "Mass for grief and hope." "In the middle of all the tragedy, I am proud to live in a country that has managed to stand tall."
Sponheim said there has been "no progress" in ascertaining what the suspect's motive might have been. But he said that investigators were studying a 1,500-page manifesto that authorities believe was published online the day of the attack.
The document, apparently compiled over a period of nine years, rants against Muslims and their growing presence in Europe and calls for a European civil war to overthrow governments, end multiculturalism and execute "cultural Marxists."
The author of the document identifies himself as Breivik and indicates he is from Norway. CNN could not independently verify that Breivik wrote the document, and Norwegian authorities would not confirm that the man in their custody wrote the manifesto, saying it was part of their investigation.
Authorities allege that he killed seven by setting off a car bomb outside government buildings in Oslo on Friday, then went 20 miles and killed at least 86 more by ambushing an island political youth retreat. The suspect was carrying a considerable amount of ammunition when he surrendered to authorities, Sponheim told reporters.
Investigators will conduct autopsies over the next few days, Sponheim said, and the identities of the victims will be released once all the next-of-kin have been notified. The death toll -- which inched up to 93 on Sunday, after a person succumbed to injuries from the mass shooting -- and may increase, police say.
At least four people have not been accounted for around Utoya island, with investigators searching the waters nearby for victims who may have drowned trying to escape the shooter. Authorities are also still trying to determine how many people died in the Oslo bombing, where the explosion badly damaged several government buildings as well as the majority Labour Party office.
They are also hunting for new evidence. On Sunday, for instance, police raided a property the suspect owned in the eastern Oslo area Slettelokka looking for explosives.
"We were there with dogs but found nothing of any value as evidence," Sponheim said.
Police said Sunday that the area around the blast site would remain cordoned off, but members of the public in the area were not at risk.
In addition to the dead, at least 96 people were wounded in the attacks -- 30 in the blast and 66 in the mass shooting.
Doctors at Oslo University Hospital Sunday were treating 31 patients injured in the terror attacks, 18 of whom were critically or seriously injured, Oslo University Hospital spokesman Jo Heldaas told CNN.
Pope Benedict XVI on Sunday offered his "fervent prayers for the victims and families, invoking God's peace upon the dead and divine consolation upon those who suffer."
"At this time of national grief he prays that all Norwegians will be spiritually united in a determined resolve to reject the ways of hatred and conflict and to work together fearlessly in a shaping a future of mutual respect, solidarity and freedom from for coming generations," according to a statement released by Cardinal Tarcisio Bertone on behalf of the pope.
U.S. Secretary of State Hillary Clinton expressed U.S. solidarity with Norway.
"The United States strongly condemns any kind of terrorism no matter where it comes from or who perpetuates it, and this tragedy strikes right at the heart of the soul of a peaceful people," she said in a statement.
CNN's Michael Holmes, Erin Mclaughlin, Chelsea J. Carter, Jim Boulden, Laura Smith-Spark, Joe Sterling, Moni Basu, Chelsea Bailey, Claudia Rebaza and Cynthia Wamwayi contributed to this report.