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A new book details an explosive affair between Jackie Kennedy and President John F Kennedy's younger brother Bobby.
The couple were thrown together in their shared grief after Kennedy, the first Irish Catholic to assume the presidency, was assassinated on November 22, 1963.
The book says that the affair was so intense that when RFK was gunned down in California, it was Jackie, not his wife, who instructed doctors to pull the plug.
On June 4, 1968, Jackie flew to Bobby's bedside in Los Angeles after he was fatally shot by Sirhan Sirhan at the Ambassador Hotel.
His wife Ethel, who the book says knew about the affair, left the room so Jackie could be alone with the dying RFK.
Bobby was already brain-dead, but neither Ethel nor Bobby's brother, Ted Kennedy were in any state to tell doctors what to do.
Author C David Heymann writes that at 1:20 a.m. on June 6, 1968, Jackie Kennedy ordered the respirator shut down and signed the consent form.
The book, "Bobby and Jackie: A Love Story," claims that everyone in the Kennedy clan, including RFK's wife Ethel knew about their romance.
"Everybody knew about the affair. The two of them carried on like a pair of lovesick teenagers," said the late Franklin Roosevelt Jr., who served as JFK's undersecretary of commerce.
"I suspect Bobby would've liked to dump Ethel and marry Jackie, but, of course, that wasn't possible."
It appears as if Bobby and Jackie may have fallen in love after Robert married Ethel Skakel in 1950. The couple went on to have 11 children and Ethel is said to have been confident that the Kennedys, traditional Irish Catholics, would not allow her husband to abandon her.
Author C. David Heymann has spent 20 years working on the book and tapes of his interviews are available in New York at the SUNY Stony Brook library. He says he even went through old files on the couple held by the FBI and Secret Service.
He backs up his claims with several interviews and pinpoints the following events where the couple were caught by others.
* In May 1964, the couple disappeared below decks during a dinner cruise on the presidential yacht the USS Sequoia. JFK's famed speechwriter Arthur Schlesinger said: "When they returned, they looked as chummy and relaxed as a pair of Cheshire cats."
* At Christmas 1964, Jackie was seen sunbathing topless with Bobby at her side at the Kennedys' Palm Beach estate.
* In July 1966, U.S. official Kenneth McKnight found found Bobby sitting on a sofa -- with Jackie "straddling his lap, her arms around his neck."
U.S. author Gore Vidals says that the one person Jackie ever loved was Robert Kennedy, while Truman Capote says the affair was "passionate," but ultimately doomed.
By 1967, as it became clear that Bobby would never leave Ethel, Jackie began dating the Greek shipping magnate Aristotle Onassis.
She was thinking of marrying him but Robert asked her to wait until after the presidential primaries.
RFK told JFK's former press secretary, Pierre Salinger, "She'll marry that man over my dead body."
Tragically, he was proved right.
Mrs. Kennedy married Greek shipping magnate Aristotle Onassis four months after Bobby's death.