John Gilbert Getty was found unresponsive in a hotel in San Antonio, Texas on Friday. The 52-year-old was one of the heirs to the family's Getty Oil fortune

The grandson of oil tycoon J. Paul Getty has died.

John Gilbert Getty, one of the heirs to the $5 billion (£3.7bn)  fortune, was found unresponsive at a hotel in San Antonio, Texas on Friday.

The cause of the 52-year-old's death has not yet been made public.

"With a heavy heart, Gordon Getty announces the death of his son, John Gilbert Getty," a spokesperson for his composer dad said in a statement.

"John leaves behind his daughter, Ivy Getty, whom he loved beyond measure, and his brothers Peter and Billy.

"His brother, Andrew, predeceased John. John’s mother, Ann Gilbert Getty, passed this September.

"John was a talented musician who loved rock and roll.

"He will be deeply missed."

The family, who once held the largest private fortune in America thanks to their oil money, have been shrouded by mystery and tragedy in recent years.

Six years ago John's brother Andrew was found dead at his LA home in 2014 after intestinal bleeding, according to  People.