LOS ANGELES -- Robert Yancy, the only child of singer Natalie Cole and grandson of crooner Nat King Cole, has died. He was 39.

Yancy was found dead Monday night at his home in the Sherman Oaks section of Los Angeles after authorities were contacted to make a welfare check. The Los Angeles County coroner's office said Tuesday that his death was reported as due to natural causes but the official cause must await an autopsy.

Yancy's aunt, Timolin Cole Augustus, told The Associated Press, "It appears to be a sudden heart attack."

Natalie Cole was 65 when she died Dec. 31, 2015, of pulmonary arterial hypertension, which led to heart failure.

Yancy, whose father was the first of Cole's three husbands, was a drummer who played in his mother's touring band and performed at her funeral in January 2016.

"We are just numb," Cole Augustus said. "The only consolation is that he's with the person he loved the most."

Yancy's father, Marvin, died of a heart attack at age 34 in 1985 when the younger Yancy was 7.

Cole Augustus said by phone from her Florida home that Yancy was "completely torn apart" upon his mother's death, but had since rebounded and was performing again.

"He was in a happy place. He was feeling good," she said. "We were looking forward to celebrating his 40th birthday."

Yancy, who went by Robbie, and his mother shared a strong Baptist faith and were regular churchgoers.

"What a woman," Yancy told mourners at Cole's funeral. "She taught me how to love. She had my back every time when I needed it. The greatest gift she ever gave me was Jesus. I cannot wait until that day that I see you again."

At the funeral, one of Cole's sisters read a condolence letter from then-President Barack Obama to Yancy.

Cole Augustus recalled her nephew as "a man of great strength and faith in God. He had an indomitable spirit. Everybody loved him."

Born Robert Adam Yancy on Oct. 14, 1977, he never married. He is survived by Cole's twin sisters, Timolin and Casey Cole Hooker, and five cousins.

Funeral arrangements were pending. Cole Augustus said Yancy would be laid to rest with his mother and grandfather at Forest Lawn in Glendale, California.

"The dynasty is up in heaven," said Cole Augustus, who along with her sister runs the Nat King Cole Generation Hope organization that works to keep music in schools.

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Associated Press Writers Robert Jablon and Andrew Dalton contributed to this report.