Anders Breivik has confessed to the shooting massacre at a youth camp, in which 69 people died, and the car bombing hours earlier in Oslo's government quarter that killed eight.

"We still think he was alone, but we cannot conclude about that. He holds back information, and that worries us," said prosecutor Christian Hatlo. 

http://www.independent.co.uk/news/world/europe/prosecutor-fears-breivik-is-holding-back-on-accomplices-2331901.html