Lettieri projected an aura of menace and ruthlessness in his film roles, which he attributed to his acquaintance with real-life gangsters, including Joey Gallo. At the age of 36, he made his screen debut in the TV film The Hanged Man. Lettieri acted with some of Hollywood's biggest screen names including Steve McQueen in The Getaway, Charles Bronson in Mr. Majestyk, John Wayne in McQ and both Marlon Brando and Al Pacino in The Godfather.

Lettieri died of a heart attack in 1975, at the age of 47, leaving two children.

Lettieri died of a heart attack in 1975, at the age of 47, leaving two children.