NEW YORK (Reuters) - The Kennedy family saga was already the Greek tragedy of modern American history, but a book alleging a love affair between Robert F. Kennedy and his brother's wife adds new pathos to the tale.
"Bobby and Jackie: A Love Story" by C. David Heymann, 64, describes the romance between RFK and former first lady Jacqueline Lee Bouvier Kennedy.
Heymann said it began in the months following the 1963 assassination in Dallas of U.S. President John F. Kennedy, known as Jack, and concluded around the time RFK announced his own run for the presidency in early 1968.
Robert Kennedy was the love of Jackie's life, Heymann said.
"Bobby and Jack were quite different," he added in an interview. "Jackie and Bobby had a much closer intellectual liaison than Jackie and John."
Heymann's research for the book dates back to 1983. His interviews focused on people close to the couple, including Pierre Salinger, president Kennedy's press secretary. His search for documented evidence includes Secret Service and FBI reports made available under the Freedom of Information Act.
The book is empathetic and recognizes that the American power elite often play by different rules, particularly in the decades before and after the World War Two when the press was not as focused on the private life of the public politician.
"There was tenderness there," said Heymann. "They were bought together by the shared grief of losing the person they were closest to."
Explaining why the public is still enamored with the Kennedy family more than 40 years after RFK was assassinated in 1968, Heymann said they were rich and attractive, and both Kennedy brothers were assassinated at the height of their power during a time when American society was in tumult.
"It's an incredible story because so much happened," Heymann said. "One was at the pinnacle of American life, the other was about to get there. Both were snuffed out. Both women were there" when their husbands were killed.
Ethel Kennedy, RFK's wife, was with him when he won the California Democratic primary election and was by his side after he was shot.
RFK had been devastated by the death of his brother in Dallas, Heymann said.
"I think in a way, (Ethel) realized Jackie could save her husband," Heymann said. "These are not ordinary people. They are powerful and rich and lead different lives. In a sense they saved each other."
Both RFK and Jacqueline Kennedy were involved with others while continuing their own affair, according to the book. Jackie was linked with Aristotle Onassis, whom she married after Robert Kennedy's death.
Heymann said the Kennedy family had made no comment about the book, his fourth based on the Kennedy family.
"They are immured to (their lives) being revealed publicly," he said. "From a public relations standpoint they have nothing to gain. If they deny it, it only sheds more publicity."
Senator Ted Kennedy, the last brother, died recently, taking what he may have known to the grave.
"He didn't want to talk about it but said it may have taken place," Heymann said before Ted Kennedy's death.
The tragedy for both RFK and Kennedy Onassis was that they could never marry.
"It would have ended Bobby's political career," Heymann said. "They were an ill-fated Romeo and Juliet."
Reporting by Nick Olivari; editing by Patricia Reaney