Oslo, Norway (CNN) -- A man who authorities say confessed to Norway's terror attacks is expected to make his first court appearance Monday, when, according to his attorney, he wants to "explain himself."

The court appearance comes as authorities continue to search for possible victims of Friday's bombing in downtown Oslo and a mass shooting at a political youth retreat on Utoya island. At least 93 people were killed and 96 were wounded in the attacks.

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 Breivik, told Norwegian TV2 that the suspect feels the terrorist attacks were "horrible," but "in his head (they) were necessary."

During the TV2 interview late Saturday, Lippestad said his client "is ready to explain himself" at Monday's court hearing.

Whether the suspect will be allowed to address the Norwegian court and under what, if any, circumstances is not immediately known.

CNN's attempts to reach Lippestad have been unsuccessful.

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The 32-year-old Norwegian has told investigators he acted alone and was not aided in the planning, acting National Police Chief Sveinung Sponheim told reporters Sunday. But authorities have not ruled out that others may have been involved or helped him along the way, he said.

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 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 the man in custody killed seven people Friday by setting off a car bomb in downtown Oslo that targeted government buildings, then traveled 20 miles to Utoya island and killed at least 86 teens and young adults in an ambush at a political youth retreat.

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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 rose to 93 on Sunday after a person succumbed to injuries from the mass shooting -- could 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, police raided a property the suspect owned in the eastern Oslo area of 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, Sponheim said.

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.