Father Carmelo was the Corleone family's priest in Nevada.
Biography
Replacing Father Hayes as the family's priest, Carmelo performed, among other ceremonies, Anthony Corleone's First Communion at Lake Tahoe. He was a close friend to the family, particularly to Carmella Corleone, who he acted as confessor to.
Trivia
Joseph Medeglia also played Father Hayes in The Godfather, leading to some speculation that they are the same character.