The Sinatra family said in a statement released to The Associated Press that the singer died of cardiac arrest while on tour in Daytona Beach. He was set to perform at the Peabody Auditorium, but the concert was canceled after he fell ill and was taken to the medical center.
He began performing musically in his early teens and occasionally appeared alongside his sister, "These Boots Are Made for Walkin'" singer Nancy Sinatra, on a number of TV variety programs.
At 19, Sinatra Jr. was the victim of a kidnapping when he was forcibly taken by three captors from his hotel room at Harrah’s Lake Tahoe. He was released after two days when his father paid the kidnappers' $240,000 ransom demands.
The kidnapping became worldwide news, and it wasn't long before authorities captured and convicted all three men responsible.