The Abominable Man of Customs(1963)

Original title: L'Abominable Homme des douanes

Two rival gangs fight over drug trafficking. An American killer named Timetti Le Muet arrives at Marseille airport to make a delivery to Arnakos' gang. He is denounced to the police, and the peaceful customs officer Camposantos is put in charge of his arrest. Following a mix-up, Camposantos is mistaken for the killer himself. Taken in by Arnakos' men, the innocent customs officer is forced to play a rather unexpected role.