Dead Joker

Chief Prosecutor Sigurd Halvorsrud's wife is found dead in front of the fireplace in the family living room. The cause of death is instantly apparent - she has been brutally decapitated. Halvorsrud immediately falls under suspicion. Then a journalist at one of Oslo's largest newspapers is found beheaded. What links these two horrifically violent crimes?
Detective Inspector Hanne Wilhelmsen is called in to lead the investigation