Death Chooses (1973)

The story of a young man who is on his own in the search for the murderer of his friend, a mail truck driver. The driver, Radek Simek, is murdered on his regular route between Radotín and Prague. Since he had little money on him that night, the police rule out a robbery motive. Radek's colleague and friend, Honza Marek, can't tell the investigators anything more. They both worked alternate shifts and had no idea how the other was spending his free time. Honza concludes that the murder is somehow related to Radek's personal life. He enlists the help of the other postal drivers and with their help tries to find the girl in the photograph found in Radek's belongings.