The Oslo police said on Monday they were setting up a special unit to investigate the twin attacks of July 22 and had collected phones, cameras and computers from the island of Utoeya for the investigation.
Setting up a new special unit "is not something we do a lot, but in a case like this that is so big and needs so much resources it's necessary," said prosecutor Paal-Fredrik Hjort Kraby, who is in charge of the Oslo police probe.
"We don't know the entire structure yet (of the new task force) but we will know in a few days," he said.
He added police had collected all of the electronic equipment found on the island of Utoeya, where far-right extremist Anders Behring Breivik has admitted gunning down 69 participants in the Labour Party youth wing's retreat.
"It was decided that all mobiles, all cameras, all iPads and all personal computers should be seized as evidence in this case," he said.
"Apart from that, we'll try to give all other personal belongings to the families and people who got hurt, but in close dialogue with AUF (the Labour Part youth wing) to make it as decent as possible," he added.
Behring Breivik's twin attacks left 77 people dead. Other than the 69 people, most of them teenagers, killed on Utoeya, eight people were killed in a bomb attack on Oslo's government quarter.