 Di Leo would make a "giallo" film with "Slaughter Hotel" starring Klaus Kinski and Margaret Lee.Following this Di Leo worked on "Caliber 9" and "The Italian Connection" which were both inspired by the writing of Scerbanenco.He followed up this film "Il Boss", a film which got Di Leo in trouble with politicians and authorities due he the films display connections between the mafia and the Italy's major party Democrazia Cristiana.