Mack's friend and producer Alvin Toney told The Daily News that the 46-year-old rap star died of heart failure.
The Long Island, New York, native was instrumental in the rise of Sean "Diddy" Combs' Bad Boy Records in the mid-1990s. His 1994 debut album "Project: Funk Da World" spawned the hits "Flava in Ya Ear," the "Flava in Ya Ear" remix and "Get Down."
Toney told The Daily News that he last saw Mack in South Carolina last week. The rapper left the music industry several years ago and settled down in the town of Walterboro.
According to Toney, Mack told him that he was ill for some time and believed he would not live very long.