Tracking A Killer by Russell Warnberg

It is the 1950's and Mick Keplar, a World War II vet finds himself becoming the Chief of Police in Brooklyn Center, Minnesota.  It is a peaceful little town until a body is found on the shores of Twin Lakes.  Keplar never had a body to deal with since he left the battlefield, where he saw several soldiers and marines die and suffers from what we now call PTSD which he deals with almost daily.  

To solve the crime, he teams up with Detective Knutson who serves in Minneapolis.  Together, they track the killers all over the upper Midwest.

Mick's wife is now pregnant, but still finds the time and energy to help him solve the crime.  Her skills as a reporter and researcher prove invaluable and her undying love help him deal with his PTSD.