Bobby Kennedy really WAS with Marilyn Monroe the night she died, says bombshell book that reveals their final conversation. And here are the explosive things she told him...

With every passing year, the questions grow louder, more insistent: just what part did John F Kennedy and his brother Robert play in the tragic death of Marilyn Monroe?

A significant one, according to Marilyn’s second husband, New York Yankee legend Joe DiMaggio, who banned the brothers from her funeral.

‘The whole lot of Kennedys were lady-killers, and they always got away with it,’ he reportedly said years later.

But, perhaps, not for much longer.

According to an explosive new book, which claims to offer proof that Monroe argued violently with then-US Attorney General Robert F Kennedy in the hours leading up to her death – and suggests he might even have drugged the actress to shut her up.

Based on never-before-seen notes and transcripts of her final – allegedly bugged – conversations, ‘The Fixer’ offers a dark insight into the private world and seedy mores of the Kennedy brothers and the louche celebrity circle surrounding them, which included the likes of Frank Sinatra and her friend Peter Lawford.

The authors suggest that Marilyn, aged 36, had issued threats to Robert F Kennedy – her lover – on the day she died and bitterly accused him of abandoning her while she underwent an operation to abort their child.

To make the case, they called on the investigation files of a police officer turned private detective called Fred Otash.

Known as 'Dreamland's ultimate fixer’, Otash is said to have bugged Marilyn's house in the weeks before her death.

The reason for the surveillance? The book doesn’t make it clear.

But the original tapes – if they existed – were said to have gone missing shortly after Marilyn was found dead on August 5, 1962, killed by a fatal overdose of barbiturates.

Authors Josh Young and Manfred Westphal claim to have found the next best thing: Otash's private notes and recordings in which he sets out what he’d found on his secret tapes.

The account begins late on August 4 when a drunk Peter Lawford hammered on Otash’s door and announced: ‘I think Marilyn is dead’.

The detective immediately set out to ‘add up the pieces’, dispatching an associate called Reed Wilson to gather evidence from Marilyn’s house. Then he listened to the secret tapes.

Otash’s notes suggest RFK had flown into Los Angeles from San Francisco earlier that same day at the instigation of Lawford, who was also the Kennedy's brother in law and had called Robert to say he was concerned about Marilyn’s state of mind.

When Kennedy first arrived at her Brentwood home, Marilyn was upset, records Otash. As he reportedly notes in brutally direct language: ‘He f****d her around 11 o'clock that morning and then he left.’

RFK returned later the same day, this time with Lawford. But Marilyn was distraught, screaming at him, ‘like there was no tomorrow’.

‘On the recording that Reed Wilson and I heard was uh . . . a serious problem,’ says Otash.

‘She had made some threatening statements to [RFK] that he had made a lot of commitments and promises to her.’

As Lawford and RFK tried to calm her, Marilyn shouted: ‘Where were you when I had to get an abortion of your kid, you no-good bastard.’

The screaming grew louder until either RFK or Peter ‘grabbed a pillow’ and used it to ‘quiet her down on the bed’ until ‘there was no more screaming going on’.

‘Maybe he gave her something,’ purportedly suggests the detective. ‘Or Peter gave her something.’

Then, Robert Kennedy is said to have left Marilyn’s house around 5.30pm, telling Lawford: ‘I’m getting my ass out of here.’

Lawford asked Marilyn if she wanted to come out to dinner with him, to which she replied: ‘I don’t feel good. I’m not up to it. I want to go to sleep. It’s been a bad couple of days for me.’

She rang Lawford twice later that night and repeatedly tried to locate Robert’s brother JFK, before calling Lawford once again saying: ‘Say goodbye to Pat. Say goodbye to the president and say goodbye to yourself because you’re a nice guy.’

Marilyn then dropped the (bugged) phone, according to Otash’s notes. Hours later she was found dead.

The Fixer’s revelations follow DailyMail.com’s exclusive serialization of ‘Ask Not: The Kennedys and the Women They Destroyed’ by Maureen Callahan, which revealed the ‘incestuous sexual competition’ between JFK and his brother RFK over Marilyn.

Callahan, a Mail columnist, suggests that Marilyn fell in love with both men after first meeting JFK at a Hollywood party in 1954 then finding herself introduced to Robert.

Both brothers had affairs with Marilyn, says Callahan – affairs which overlapped.

Even on the night she sang 'Happy Birthday' to JFK at Madison Square Garden in May, 1962, Marilyn had slept with RFK in her dressing room beforehand.

Later that evening, Marilyn was captured in the only known photo of her with the Kennedy brothers – the men who, says Callahan, bear a heavy responsibility for her fate.