Olsen studied criminology at the University of Oslo and philosophy at the University of Tromsø.
Many of his books have been hits with critics. He has worked as a travel agent, taxi driver, night porter, journalist, translator, office worker, literary critic, education consultant, and teacher. He was head of Norsk Forfattersentrum (1989-1991), head of arrangements for the Brage Prize (1991-1995) and deputy head of the Norwegian Authors" Union (1997-1998).\r\nFrom 1992-1996 he was editor of Bokklubben krim og spenning.
Sergeant Norwegian Field Artillery, 1979-1980. Member Norwegian Writers' Union, Crime Writers' Association, Mystery Writers American.
Married Anne Gro Dyvik, February 26, 1988 (divorced July 1995). 1 child, Torkild Dyvik.