In front of 15,000 people, Monroe then sang Happy Birthday, filling in the name with “Mr President”, in what is now remembered as a seductive, sultry voice, but was actually just the result of breathlessness. The performance was racy, packed with innuendo (her relationship with JFK never looked more suspicious) and has since become a milestone moment in Monroe’s life.

It was, also, one of her last public appearances before her untimely death only a few months later. Monroe, beneath the sex-symbol status and folksy charm of her movies, spent the last weeks of her life troubled and battling a psychological tempest that had raged in her mind since childhood.

Marilyn Monroe’s childhood

Before she was blonde Hollywood A-lister Marilyn Monroe, she was brunette Norma Jeane Mortenson. From her birth on 1 June 1926 to the age of 16, Norma was bounced to a dozen foster homes around California as her father was absent and her mentally unstable mother, Gladys, was habitually institutionalised so couldn’t provide for her daughter. Few of Norma’s childhood experiences, which involved a stint in an orphanage, were happy. Her mother’s erratic behaviour left a traumatic mark on a young Norma when, as a toddler, she was kidnapped by Gladys from her foster parents and stuffed, screaming and terrified, into a bag. As Norma blossomed into a teenager who looked older than she was, she suffered sexual abuse, including an allegation of rape.

Rare solace came when her mother’s best friend, Grace McKee, temporarily became her guardian. Together, they would go to the movies, where Norma would be entranced by the romances and came to idolise the actress – and original blonde bombshell – Jean Harlow. Increasingly drawn to the bewitching power of the silver screen, Norma pictured herself as a Hollywood star and amused herself pretending her estranged father was the legendary actor Clark Gable.

Then, at the age of 16, Norma made a drastic decision to get out of the cycle of foster care: she married her 21-year-old boyfriend, Jim Dougherty. The marriage was not unhappy, but Norma dreamed of bigger things than being the housewife of a Merchant Mariner, especially when Jim was deployed to the Pacific during WW2. Norma, like many wives of military men, joined the war effort by working on a factory assembly line, inspecting parachutes and varnishing fuselages.

Norma Jeane Mortenson becomes Marilyn Monroe

A factory job is hardly the most obvious place for a budding actress to get her break, but it was exactly where Norma got noticed. A photographer came to the factory to shoot morale-boosting images, and was instantly drawn to Norma’s wholesome good looks.

On that photographer’s advice, Norma began modelling and by the time Jim had returned, she was gracing dozens of magazine covers.

The year 1946 was a time of great change for Norma. She garnered the attention of Ben Lyon, an executive at 20th Century Fox and was offered a movie contract. She divorced Jim, dyed her hair a golden blonde and changed her name. She chose the surname Monroe as it was her mother’s maiden name, while Marilyn came from the famous Broadway star, Marilyn Miller. Norma Jeane was no more; Marilyn Monroe was born.

To go with the new look, the inexperienced Monroe plunged into acting, dancing and singing classes while she appeared in a few non-speaking roles. But, before stardom beckoned, her $125-a-week contract with Fox ended and Monroe returned to modelling to pay the bills.

In 1949, she was convinced to pose nude for the paltry fee of $50. Four years later, Hugh Hefner paid $500 for the photos and printed them in his new magazine, Playboy, making Monroe the inaugural Playmate of the Month.

By then, her acting career was back on track. She won a lot of fans with her bit-performance as the ditzy mistress of a criminal in esteemed director John Huston’s The Asphalt Jungle and got plaudits for her comedic turn in All About Eve, both released in 1950.

Fame kept coming for Monroe so that by the time Niagara, where she plays a femme fatale planning to kill her husband, hit cinemas in 1953, she was top billing. This was followed by a string of quickfire hits – Gentlemen Prefer Blondes (1953), How to Marry a Millionaire (1953) and There’s No Business Like Show Business (1954). The value of her looks in these successes was not lost on the executives guiding her career. They persuaded her to have cosmetic surgery to trim the tip of her nose and correct a minor overbite. With every movie’s release, Monroe was a bigger star, known across the world. But the cracks in her frame of mind were already widening.

Her marriage to handsome baseball star Joe DiMaggio ended after less than a year when she filed for divorce in October 1954 on the grounds of ‘mental cruelty’. A catalyst for their separation came when Monroe filmed the now-immortal scene in Billy Wilder’s The Seven Year Itch where her skirt is blown up by the gust from a subway grate.

Filming was watched by a large crowd of leering spectators, which incensed DiMaggio. Monroe’s insecurities were affecting her work, and leaving a string of lovers behind her. Sometimes, she made herself ill with anxiety and she regularly frustrated fellow actors and directors with her dramatic lack of punctuality. A total of 28 days had to be added to the schedule of Let’s Make Love (1960) as a result of her no-shows.

Marilyn Monroe’s later film roles

The mid-1950s saw the vulnerable Monroe grow tired of her standard dumb blonde roles. In attempts to pursue more serious acting, she studied at the revered Actors Studio in New York under the great Lee Strasberg and established Marilyn Monroe Productions. When she did return to the big screen with Bus Stop (1956), playing a kidnapped saloon owner, she won critical acclaim, with one puckish review reading, “Hold on to your chairs, everybody, and get set for a rattling surprise. Marilyn Monroe has finally proved herself an actress.” But happiness continued to elude her. While filming The Prince and the Showgirl with Sir Laurence Olivier, her weight fluctuated so wildly that the costume designer crafted several sizes of each dress. She remarked afterwards, “I have two ulcers from this film, and they’re both monogrammed MM.”

In a surprise turn of events, Monroe married the intellectual playwright Arthur Miller in 1956 – prompting the headline ‘Egghead weds Hourglass’ – but the marriage disintegrated over four years, with Monroe being involved in multiple affairs. She was eager to have children, but after a miscarriage and another pregnancy with complications, she grew distraught and dependent on popping pills and gargling booze. She was in such a bad way that while filming Some Like it Hot (1959), for which she won a Golden Globe, she was unable to recall simple lines.

She was in such a bad way that while filming Some Like it Hot (1959), for which she won a Golden Globe, she was unable to recall simple lines

On one day of the shoot, it needed well over 60 takes just to get the line “It’s me, Sugar!” A troubled pregnancy during filming, which ended in her second miscarriage, only saw Monroe sink further into depression, and director Billy Wilder facing the full brunt of her ire. As well as her expected tardiness (leaving her co-stars Jack Lemmon and Tony Curtis on set for hours in women’s make up), Monroe demanded that her role be re-written so she had a bigger part in the jokes. This led to the inclusion of Monroe’s memorable entrance to the movie – being struck with a jet of steam as she shimmies down a train platform. Her career would never reach such heights again.

Monroe split from Miller in 1961, but her last complete role was in the movie he penned, The Misfits. Filmed the same year as their break-up, it put a terrible strain on Monroe and drove her to pills and drink – and put her in hospital for ten days. In June 1962, illness and depression led to her being kicked off the aptly-titled Something’s Got to Give. By now, the troubled actress was reliant on medication and daily sessions with her psychiatrist, Dr Ralph Greenson.

Marilyn Monroe’s death

Greenson was one of the first to find out when Monroe’s body was discovered in the early hours of 5 August 1962. Monroe, 36, was found face down on her bed in her Los Angeles home, with several bottles of pills on a nearby table. The hasty coroner’s report stated the cause of death as ‘probable suicide’ from acute barbiturate poisoning.

Inconsistencies in statements and rumours she was connected not just to the Kennedy brothers – serving as President and Attorney General – but also the mafia saw a flurry of conspiracy theories proliferate.

Monroe’s star shone intensely, albeit briefly. Hers was a complex life of contrasts, confounding those who dismissed her as a fatuous airhead. She was born poor, but died a multi-millionaire; she had an air of vulnerability about her, but was headstrong in achieving her dream; she was desired by men, but easily manipulated by some of them; she had no problem finding lovers, but struggled to find love. And finally, she spent her life running away from her unhappy childhood as Norma, but even as cinema superstar Marilyn, she couldn’t escape her inner demons.

Monroe’s star shone intensely, albeit briefly. Hers was a complex life of contrasts, confounding those who dismissed her as a fatuous airhead

Initially, the discovery of Marilyn Monroe’s body on 5 August 1962 appeared to be a clear-cut case of suicide. Monroe was alone in the house – the alarm was raised by her housekeeper Eunice Murray who telephoned Monroe’s psychiatrist Dr Ralph Greenson – and there were empty bottles of pills near the body. There was no question that Monroe was fighting mental issues so suicide was well within the realms of possibility.

Theories have persisted, however, claiming that Monroe was murdered, possibly by Greenson himself or even on the orders of President John F Kennedy or his brother, Attorney General Robert Kennedy. Both were believed to be Monroe’s lovers and, fearing that she would reveal the affairs to the press, wanted to keep her silent.

According to sensational claims made in the recent book The Murder of Marilyn Monroe: Case Closed by investigative journalists Jay Margolis and Richard Buskin, it was Robert that ordered the murder after a tense meeting at Monroe’s home on 4 August. Greenson, allegedly another lover of Monroe’s, administered the fatal injection while an ambulance paramedic stood nearby.

Although these claims are unproven and sensational, there are reasons to question the coroner’s report of ‘probable suicide’. Chiefly, Monroe had recently heard the good news that Fox were hiring her and she was excited about the immediate future. There was also speculation that she was close to reconciliation with her second husband, Joe DiMaggio.