JFK files: Bobby Kennedy warned about book accusing him of plot to MURDER Marilyn Monroe

Both Mr Kennedy and the director of the FBI received a letter warning of Frank Capell’s 1964 book, The Strange Death of Marilyn Monroe.

It claims Bobby Kennedy had the star killed when she threatened to expose their long-standing affair.

Mr Capell’s book claimed: “Miss Monroe’s involvement with Kennedy ‘was well-known to her friends and reporters in the Hollywood area’, but was never publicised.”

The author was said to have concrete evidence of an affair including written evidence, tape recordings and living witnesses attesting to “the closeness of their friendship.

The book went on to theorise that Mr Kennedy, the brother of , “had Communists ‘murder’ Miss Monroe” when she threatened to go public with their affair.

Including direct citations from the book, the letter reads: “The author suggests that Miss Monroe ‘was led to believe his intentions were serious’, and that Kennedy had promised to divorce his wife and marry her.

“When he failed to do so, the book charges, she ‘threatened to expose their relationship’, which would have ruined his presidential aspirations.

“It was then that Kennedy decided ‘to take drastic action’.”

Bobby Kennedy was accused of having Communists make Marilyn Monroe’s murder appear to be a suicide.

The author pointed out that the actress’ doctor was a Communist, so it would be easy for conspiracists to gain access to her.

The letter points out that these accusations had already been levelled at then-Attorney General Kennedy and branded false – but the government was nonetheless concerned about the publication of the explosive book.

The Strange Death of Marilyn Monroe received little attention from the public, however its sensational claims throw weight behind previous speculation of a sordid affair between Marilyn Monroe and Bobby Kennedy.

Last year, a new piece of evidence offered further proof of an affair between the two, when a letter from the Attorney General’s younger sister, Jean Kennedy Smith, was found in Miss Monroe’s belongings.

It says: “Understand you and Bobby are the new item!

“We all think you should come with him when he comes back East!”

The were released on Thursday after decades in the dark after , in full.

Some 2,800 of the 3,200 records have been published by The National Archive as the remaining papers stay under lock and key.

The remaining documents will be subject to a 180-day review to determine why they .