A new book, "Sinatra: The Life," examines how "The Chairman of the Board" built his career on raw talent - and possible mob connections.
It was written by biographers Anthony Summers, a former BBC investigative reporter, and his wife, Robbyn Swan.
Summers tells The Early Show co-anchor Harry Smith that Sinatra's roots in Sicily put the showbiz legend much closer to the Mafia than he ever let on.
"Going around the churches in Sicily, we tracked (Sinatra's grandparents) back to a village…right in the heart of Mafia country. And they lived in the same little street as Lucky Luciano, who virtually created the American Mafia.
Luciano was the mob boss who was a model for "Godfather" Vito Corleone.
Sinatra's parents were saloonkeepers during Prohibition, which in and of itself meant they had to have serious mob connections to stay in business, Summers points out. "And Sinatra's father once came home bleeding and battered one night. He had been helping guard one of the trucks that was carrying liquor," he adds.
Sinatra's mother's brothers "were involved in some pretty shady dealings during Prohibition," and murder was one of the charges, Swan says.
The authors document a more than circumstantial affiliation between Sinatra and crime bosses Luciano and Sam Giancana.
Summers and Swan show that Sinatra worked tirelessly campaigning for John F. Kennedy's election, and that Sinatra was unceremoniously snubbed by the president once he was elected.
They credit Sinatra with deliberately pairing Judith Campbell, with Giancana's help, with Kennedy, and they draw a connection between mob support and the 1960 election.
"I think this is perhaps, for the historians, one of the breakthrough things we put together in the book," Summers asserts. "Judith Campbell was the mistress who people always say, not quite correctly, JFK shared with Sam Giancana, the Mafia boss from Chicago.
"Whereas, the important thing is that she said, Judith Campbell, when exposed, she said that she had been a young woman, sort of disingenuous, divorcee, age 24, and that she had not known Sam Giancana or the mobsters at all before she met JFK.
"Unfortunately," Swan says, picking up the story, "the Kennedy White House under Bobby Kennedy then went after Giancana, intensely. And Giancana blamed Sinatra. He blamed his intermediary.
"(At a hotel) in early 1961, Sinatra sent down for room service and what came up on the room service platter when he opened it was the skinned head of a lamb, a very frightening threat if you know anything about the Mafia."
Summers and Swan interviewed comedian Jerry Lewis, who says Sinatra worked as a courier for the Mafia and was nearly caught in a New York airport carrying a suitcase stuffed with $3.5 million.
They also chronicle Sinatra's tumultuous marriage to Ava Gardner, for whom Summers says Sinatra had an "absolute obsession," even asking Gardner for reconciliations minutes before marrying two other wives.
"When she died in 1990," Summers continues, "he forced himself to go and perform. It's one thing we're leaving out here, is the extraordinary talent and the marvelous professionalism of this man. He went and performed at Albany, N.Y., carrying a bottle of Jack Daniels, and he sang. He was really mourning Ava on stage."