Rocco and the Nightingale by Adrian Magson

In this mystery set in 1960s France, a rural police inspector contends with a bounty on his head while probing the murder of a Paris hoodlum.
When a minor Paris criminal is found stabbed in the neck on a country lane in Picardie it looks like another case for Inspector Lucas Rocco. But instead, he is called off to watch over a Gabonese government minister, hiding out in France following a vicious coup.
As if that wasn't enough to keep him occupied, Rocco discovers that there is a contract on his head taken out by an Algerian gang leader with a personal grudge against him.
With time running out, to catch a murderer and to save his own life, Rocco will be tested like never before.
Perfect for fans of Peter May, Donna Leon, and Georges Simenon.