Bobby Kennedy got involved in a messy sexual affair with Marilyn in the summer of 1962 when he was sent out to Los Angeles by his brother Jack to convince the screen goddess to stop calling the President at the White House.

Marilyn Monroe’s death on August 4, 1962 was not a suicide but a murder orchestrated by Bobby Kennedy to silence her as she was about to reveal all the dirty Kennedy family secrets she kept logged in a little red diary. He had co-conspirators in her murder - his brother-in-law, actor Peter Lawford, and Marilyn’s psychiatrist, Dr.

Ralph Greenson who gave the star a fatal injection of pentobarbital to the heart.

Those are the explosive allegations detailed in a blockbuster new book by writers Jay Margolis, a long-time investigative reporter and Monroe expert, and Richard Buskin, a New York Times bestselling author of 30 non- fiction books.

‘It was the craziest thing he ever did – and I was crazy enough to let it happen’.

It was a murder allegedly witnessed by ambulance attendant James C.

Hall, who arrived at the film star's home and saw Monroe’s psychiatrist Dr.Greenson inject Marilyn directly into her heart with undiluted pentobarbital, brutally breaking a rib with the needle.The volume - The Murder of Marilyn Monroe: Case Closed - claims to blow the lid off the world’s most notorious and talked-about celebrity death through eyewitness testimony and interviews, Mail Online can exclusively reveal.Torn between two lovers: Marilyn had affairs with both Kennedy brothers, the authors claim.She was obsessed with Jack and Bobby and wrote about their trysts and other Kennedy secrets in a little red book Fallen idol: The death of Marilyn Monroe has generated 50 years of wild speculation about how she really died.Now two respected authors say they have put that speculation to rest with proof that Bobby Kennedy arranged the murder of the iconic star ‘Bobby Kennedy was determined to shut her up, regardless of the consequences’, Peter Lawford later revealed, according to the authors, feeling wracked with guilt over the star’s murder.