A person claiming to be Norwegian mass-killer Anders Breivik's second in command has issued a warning of more terror, sparking a police investigation.
An email sent to several politicians and newspapers in the country demands Breivik's release and reportedly threatens to destroy the higher echelons of Norwegian society.
The letter's author purports to be deputy commander of the Knights Templar - of which Breivik previously said he was leader, but which experts told his trial probably did not exist.
It says: "I hereby present myself as cell two and deputy commander of the Norwegian resistance movement.
"I, with my soldiers, give all due respect to our people, our culture and our ethnicity (and) warn all advocates of multiculturalism against this war we are now so deeply in.
"Now it's time for us and our commander Breivik to get recognition on the political landscape of Norway and Europe."
A newly-released report into the massacre on July 22 , 2011 - in which a total of 77 people were killed during a bomb attack in Oslo and shooting spree on a nearby island - concludes that security services could have stopped the atrocity.
And the Norwegian Police Security Service, which is investigating the threatening letter, believes it will be able to find its author.
Police attorney Anne Karoline Staff said the letter would have been investigated irrespective of the critical report on security services' handling of the killings.
"The gravity of the case lies in the content of the letter, the references in the letter, the backdrop with the acts on July 22 last year, and not least Anders Behring Breivik's manifesto," she said.
"One has to be an optimist. I think we will find the perpetrator."