[2][3] Karin Mathisen was born on 6 November 1954 in Sandefjord,[1] in Vestfold county, Norway.

For a time she worked in hospitals, and nursing homes and assisted with the rehabilitation of drug addicts.

[3] She is the author of the internationally successful Inspector Konrad Sejer series of crime novels, which have been translated into 25 languages and honoured with several awards.

La ragazza del lago, internationally released as The Girl by the Lake, is a 2007 Italian thriller-drama film directed by Andrea Molaioli, in his directorial debut.

(also featuring Inspector Jakob Skarre): The character of Sejer appeared in a series of Norwegian TV adaptations starring Bjørn Sundquist in the role, with Christian Skolmen as Sejer's partner Jacob Skarre.