I was suprised to learn that Al Lettieri died so young. Here's info from Wikipedia (which cannot be entirely trusted, as it lists credits after Lettieri died):

Al Lettieri (born Alessandro Lettieri, February 24, 1928 – October 18, 1975) was an Italian American actor, best known for his portrayal of Virgil "The Turk" Sollozzo in The Godfather.

Lettieri convincingly projected a remarkable aura of menace and ruthlessness in his film roles, which he attributed to his acquaintance with real-life gangsters, including Joey Gallo. He made his on screen debut in the made for TV film The Hanged Man. Lettieri played the villain against some of Hollywood's biggest screen names including chasing Steve McQueen in The Getaway, Charles Bronson in Mr. Majestyk, and John Wayne in McQ.

Lettieri died of a heart attack in 1975, at the age of 47, leaving two children. His daughter, Alda Lettieri, is a stage actress in New York City.