Without Apparent Motive (1971) on Netflix

Plot summary

Commissaire Stéphane Carella investigates a string of killings in Nice in which apparently unconnected people are each shot once from a long-range 0.22 rifle. The first victim is Forest, a prominent local businessman; his widow offers nothing, but his stepdaughter Sandra mentions an associate, Barroyer, who is killed the same way within the day. Sandra also finds her stepfather's diary. The police learn that both men moved funds through an astrologer and drug dealer, Hans Kleinberg, who is shot that day too. Carella, unmarried, runs into Jocelyne, an old flame. Four deaths in two days leave his superiors frantic, and though the victims are linked to money laundering, narcotics and prostitution, no motive for the murders adds up.