Rest in peace, Robert Yancy.
Natalie Cole's son died on Monday, a rep for the Cole family confirms to ET. Yancy was 39.
WATCH: Natalie Cole's Family Releases Singer's Cause of Death
Yancy died of a heart attack, with law enforcement listing his cause of death as natural causes pending the completion of an autopsy and toxicology test. Drugs were not involved in Yancy's death.
Family members say that Yancy, who worked in the music industry, had never abused drugs and was "turning his life around."
Cole fought drug addiction for years until her 2015 death, while Yancy's father, pastor and gospel musician Marvin Yancy, died of a heart attack at age 34.
RELATED: Natalie Cole's Family and Friends Gather in Los Angeles to Celebrate the Legendary Singer's Life
ET sat down with Cole's sisters in 2016, shortly after her death, where they opened up about their last days with the legendary singer. See more in the video below.