Synopsis:There's a short (English) interview with him on a German site here.
In the course of a routine police raid, Detective Inspector Frank Frolich of the Oslo Police saves Elizabeth Faremo from getting inadvertently caught in crossfire. By the time he learns that she is the sister of Jonny Faremo, wanted member of a larceny gang, it is already too late. He is obsessed. Suspected, suspended, and blindly in love, Frolich must find out if he is being used before his life unravels beyond repair.
I particularly like this Q & A:
Q: How did you get into crime mysteries?
K.O. Dahl: It is a long story, which involves one beautiful woman, one late night, some bottles of champagne, a police car, an angry husband and a typewriter.
There's also a Norwegian website for Dahl.