Marilyn Monroe's last weekend...

On Sunday, August 5, 1962, the body of Marilyn Monroe was found naked and face-down on her bed at her home on Fifth Helena Drive, at the end of a quiet cul-de-sac in Brentwood, California. She was 36 years old.

'The long troubled star clutched a telephone in one hand. An empty bottle of sleeping pills was nearby,' reported the Associated Press that morning.

Long before she was officially discovered dead on the Sunday, neighbours had seen a mysterious - and still unexplained - ambulance parked in front of the film star's residence on the Saturday evening.

Final days: In a never-before-seen photograph, Buddy Greco poses with Marilyn Monroe, as Frank Sinatra looks on, at the notorious Cal-Neva Lodge

They also reported a helicopter hovering overhead. Raised voices and the sound of breaking glass were also heard that night.

Other neighbours reported that in the early hours a hysterical woman - who remains unidentified - had screamed: 'Murderers! You murderers! Are you satisfied now that she's dead?'

For 48 years, Marilyn Monroe's death - and the events that later came to light: reports of a visit that night by her lover Bobby Kennedy; of an ambulance that took her away breathing and brought her back dead - has remained one of Hollywood's most enduring and tantalising mysteries.

I was a reporter in New York at the time and flew to Los Angeles that morning to cover the story. I can still recall the haunting sound of the antique wind chimes - a gift to her from the poet Carl Sandburg - that hung beside her pool, on which floated a child's plastic yellow duck. It was a melancholy sight. I had known her a little and it made me sad.

I don't think the death of any other movie star has intrigued the public as much as Monroe's. Was it murder? Suicide? An accidental overdose?

Some have suggested that her former lover Frank Sinatra, who she had come to rely on, could have saved Monroe - but chose to turn his back on her when she was at her lowest ebb.

The questions and doubts, the revelations and scandals that always follow the sudden death of a celebrity - especially beautiful ones, who die young - have continued to fascinate me, as have the unaccountable silences of several key witnesses.

But after nearly 50 years there seemed little more that could be said or discovered.

Until now. In London as part of a two-month nationwide tour of his much anticipated show, Swinging Las Vegas, the legendary American jazz pianist and singer, Buddy Greco - who once rubbed shoulders with Frank Sinatra and the Rat Pack and now lives in Essex with his fifth wife - talked to me about the mysterious weekend Monroe spent at the notorious Mafia haunt, the Cal-Neva Lodge, in Lake Tahoe, Nevada, five days before she died.

Before the fall out: An undated picture of the actress talking to former lover Sinatra at a casino in Nevada

It is the first time anyone has revealed first-hand what happened there. Now 83, he is sitting in Locale Italian restaurant on London's South Bank. Still handsome, with a trademark smile, the performer made famous by such hits as The Lady Is A Tramp and Girl Talk remembers Monroe, who was exactly his age, with both fondness and sadness.

Uncertainty, contradiction and tragedy have always surrounded the mysterious and fateful weekend of July 28 and 29, 1962.

Those who were there - including her former lover Sinatra (who had invited her to Cal-Neva), Dean Martin, Sammy Davis Jnr., Juliet Prowse ( who was engaged to Sinatra), Peter and Pat Kennedy Lawford, and Paul 'Skinny' D'Amato, who managed the Cal-Neva Lodge for its owners Sinatra and his partner, the notorious Mafia godfather Sam Giancana - are either dead or still refuse to talk about what happened during those 48 hours.

Indeed, while more than 100 books have been written about the life and death of the woman who was probably the greatest sex symbol of the 20th century, not one of them has managed to penetrate the mystery or fill the lacuna in our knowledge of Monroe's final days at Cal-Neva.

And yet these days contain vital clues to her tragic end. Monroe was certainly in a dreadful state at the time. Robert Kennedy - who had inherited Monroe as a mistress from his brother, President John F. Kennedy - had just ended their five-month affair when she took off for Cal-Neva, and the last weekend of her life.

'When she arrived that Saturday, you'd never believe that she had a care in the world'

Buddy Greco recalls of her demeanour later that weekend: 'She was fragile, very fragile - well, she'd gone.' Many blamed the Kennedys.

'Marilyn was distraught and heartbroken. She felt the Kennedys had handed her around like a piece of meat,' Rupert Allan, her publicist and one of her last true Hollywood friends, had said earlier.

Her grip on reality - already weakend by mental illness, drink and drugs - was certainly shaky.

How else to explain the fact that she had persuaded herself Bobby really would divorce the mother of his seven children.

As the attorney general of the United States, a member of the most famous Catholic family in the land and a politician who had just been named Father of the Year, he was never likely to run off with a thrice married Hollywood sex symbol.

When the penny dropped, Monroe felt abused. She had always known how to stage a scene to get what she wanted and she had threatened the Kennedys.

'If I don't hear from Bobby Kennedy soon I'm going to call a press conference and blow the lid off this whole damn thing - I'm going to tell about my relationships with both Kennedy brothers,' she told Robert Slatzer, an ex-lover, a few days earlier.

Those close to Monroe knew that this was no idle threat. It had been a bad time for Monroe. She was hurt and wanted revenge, as only a spoiled movie star could.

A few weeks earlier, she had also been publicly humiliated by 20th Century Fox's studio boss Peter G. Levathes.

Fed up with her chronic absenteeism - in 35 days of filming, she had turned up a dozen times and when she did arrive she was so heavily medicated she could not remember her lines - he had fired her from Something's Got to Give, the film she was making with Dean Martin.

Costly affair: A rare image of Marilyn with President John F. Kennedy (right) and his brother Robert F. Kennedy together after JFK's 19 May 1962 birthday party

He also issued a $500,000 breach-of-contract suit against her and replaced her with Lee Remick.

Although her lawyers were in the middle of patching things up with the studio and were confident that Something's Got To Give would resume filming in the last week of August, with Monroe reinstated, she was still drinking heavily and bingeing on pills.

Of course, she could still shine when she wanted to. But by now her gloss was too often just a thin veneer.

Despite her depression, she initially appeared in good shape when she arrived at Cal-Neva, after flying there on Sinatra's private plane.

'When she arrived that Saturday, you'd never believe that she had a care in the world,' recalls Buddy Greco. 'I was sitting with Frank [Sinatra], Peter Lawford and a bunch of other people, outside Frank's bungalow, when a limousine pulls up and this gorgeous woman in dark glasses steps out,' he says.

'She's dressed all in green - everything green: coat, skirt and scarf. Before I realised who it was, I thought: "My God, what a beautiful woman. No taste in clothes, but what a beautiful woman!"

'I knew that she'd been to my concerts and shows. She was a regular at the Crescendo club in Hollywood where I often played.

'It has been suggested that Sinatra invited Monroe to Cal-Neva Lodge to urge her to keep her mouth shut about her affairs with the Kennedy brothers'

'We'd said hello a few times, but were never properly introduced. When Frank introduced us, I said: "You won't remember me, but I was the piano player when you auditioned for the Benny Goodman band in 1948."

'She got emotional at that and hugged me. She had such warmth - and I was moved. Somebody took some wonderful shots of that moment, of us hugging.'

Indeed, Greco still has six black and white prints from a roll of film taken over the course of that weekend. He had kept more in a safety deposit box at the World Trade Center, but they were lost in the 9/11 terror attacks.

'The people in those pictures were among the great entertainers of our time - Marilyn, Frank, Dean Martin,' says Greco.

'It was an unrepeatable moment, a time that would never happen again. July 1962.'

But by the end of the first evening, a darker Monroe was beginning to emerge. Greco had finished his first performance in the hotel's lounge and had joined Sinatra and the other guests at Sinatra's regular table.

'It was a wonderful time, a magical weekend. It is so hard to describe now but it was maybe the best time of my life.

'Then suddenly the room went silent and very still. It was surreal. As if somebody had turned the sound off. I looked at Frank. I could immediately tell he was furious. His eyes were like blue ice cubes.

'He was looking at the doorway where Marilyn was stood, swaying ever so slightly.'

Given her history of chronic alcohol and drug abuse, it was an ominous sign. Indeed, Sinatra had fallen out with Monroe over her addictions before.

He had opened the refurbished Cal-Neva just a month earlier and Monroe had got blind drunk on that occasion, too.

Screen icon: Her death has intrigued the public for decades

He had tried to help and she still held him in high esteem, but Sinatra was tiring of her antics.

'She was still in the same green outfit she'd worn all day,' says Greco. 'But the woman I'd met that afternoon - smart , funny, intelligent, fragile - had gone.

'Now she looked drunk and, well, defiant. She was clearly angry and I think I heard her say: "Who the f*** are they all staring at?"'

Sinatra - who was obviously irritated by her erratic behaviour - acted fast.

'It was clear Sinatra was worried. She was in a state where she could have said anything,' says Greco.

This would have been a major concern for many of those around the table. Monroe, after all, knew an awful lot of secrets - and, in her condition, might have been prepared to share them.

'Sinatra motioned to his bodyguard - Coochie - to get her out of there. Coochie, a big guy, escorted her out. Actually, he picked her up and carried her out. It wasn't the star we were used to seeing.'

The incident upset Buddy Greco. He had felt such warmth and vulnerability in her only a few hours earlier and could not understand how she had changed so terribly and suddenly.

'She was on my mind,' he says. 'I was worried about her. I went outside to find out whether she was okay. I knew that she had taken accidental overdoses in the past.

'I found her by the pool. There was nobody around. It was late and the pool was deserted.

'Maybe it was the moon but she had a ghostly pallor. It still didn't occur to me that she might be a woman not long for this world.

'She was distressed, out of it, but that was all. Maybe her friends were used to seeing her like that but it worried me. Anyway, we talked.

'I walked her back to her bungalow in the complex reserved for the guests of Frank and Giancana where we all stayed.

'I thought that the next morning I could put her with Pat Lawford [the Kennedys' sister], who was her companion, and make sure she got back to L.A. safely.

'But the next day when I called, she had already left. That was the last time I saw her.' So does he think that Sinatra had finally lost patience with Monroe and by abandoning her had left her to her fate?

'That's a possible scenario,' Greco answered thoughtfully. 'After she had created that problem, he certainly wanted her out of there. He could be quite firm with her.'

Indeed, it has been suggested that Sinatra had invited Monroe to Cal-Neva Lodge that weekend to urge her to keep her mouth shut about her affairs with the Kennedy brothers.

The question is: had he already succeeded when he told her to go? Or given it up as a bad job - and thrown her back to the wolves?

Either way, after being ejected out of that bar by one of her closest friends, the clock was already ticking. And within five days, she was dead.