I due evasi di Sing Sing (1964)

Two attendants in a public toilet in New York save the life of the Mafia boss Attanasia. Attanasia turns one of them into a successful boxer by setting up his matches and makes the other into his right hand. When a gang war starts the two are accused of the murders and are sentenced to death. When the execution day comes they refuse to leave their cell, even when they are proved innocent.