Olsen was born in Bergen.[1] He made his literary debut in 1985, with Svart, svart – og et tynt lag hvitt, on disillusioned and whisky-consuming youngsters.[2] Further novels are Libero. Loven vest for Geilo (1986),[1] about two football-loving young boys,[2] Den eneste andre (1989), where the protagonists are two vagants,[2] and the sequel Blodets sang from 1991.[2] The 1994 novel Den sanne historien combines social and psychological aspects of the 1990s.[2] The novel Manndomsprøven (1997) is about a maturing young boy, while Fredstid (2000) is a love story set in the late 1930s.[1] In the crime fiction novel Mørk april from 1987, Olsen introduced private investigator "Aron Ask", a former freelance journalist, who eventually appeared in a number of novels, including the sequels Overspill (1990), Rødt regn (1992) and Isdronningen (1995),[2] as well as in Oslo-piken (1998), Tusenårsriket (2002), Nattmusikk (2005) and Bakmennene (2009).[1] His children's novels include Tigrene tar avspark from 1996, and Tigrene finner formen from 1997.[2]
Olsen is a literary critic of crime fiction for the newspaper Aftenposten.[1]
