WITH her platinum blonde hair, scarlet pout and trademark wiggle, Marilyn Monroe was the 20th Century's ultimate sex symbol.

A single hair from the Hollywood icon was put up for auction, recently, at an asking price of almost £500 - clearly, 40 years after her death, our fascination with her shows no signs of diminishing.

She might have been dead longer than she was alive, but she remains the embodiment of feminine sexuality.

Her continuing appeal may be explained by her beauty and her overwhelming sensuality, but it's her early death which helped fix her image forever.

As with James Dean, she's been preserved in our minds as someone who is eternally young. Had she lived, she would have just celebrated her 76th birthday.

And while today we know everything from the toothpaste a celebrity prefers to what they had for lunch, she belonged to an era when studio executives and agents strictly controlled a star's image. As a result there are no open-hearted autobiographies and in-depth interviews.

When Monroe died, she took many of her secrets with her. Maybe this is why she's continued to captivate the public imagination for so long. We can only speculate about what she was truly like.

Hundreds of books detailing her life cater to this desire for knowledge and debate rages about her life and death, especially the latter, aged 36 on the night of August 4, 1962, which is surrounded by controversy.

Officially recorded as suicide after a sleeping pill overdose, conspiracy theories continue to flourish. Many Americans believe she was murdered by the US Government as a result of her affairs with John F Kennedy and his brother, Bobby.

But, whether it was a simple suicide, an accidental overdose or murder, there are certainly inconsistencies in the events of that night. There was autopsy evidence that Monroe didn't die from orally ingesting sleeping tablets, and the scene of death appeared to have been tampered with. Important post-mortem tissue samples also disappeared.

Perhaps most telling were the telephone calls, costing more than £100, which were deleted from the phone records.

One of the last people to interview and photograph Monroe, George Barris, author of Marilyn Her Life in her Own Words (Citadel Press, £24.95) believes she was at a point in her life when she was incredibly happy and had no reason to end it.

Although he has no proof, he strongly believes she was murdered.

Her life has also been the subject of intense interest and debate. Born Norma Jean Mortensen on June 1, 1926, she was later baptized with the surname Baker. Her childhood, though later stylised by the actress as being very grim, was certainly an unhappy time which saw her passed around many foster homes.

Many believe it was during those tentative years that she developed the desire to succeed which characterised her later life. Monroe herself once said: "No one ever told me I was pretty when I was a little girl. All little girls should be told they're pretty, even if they aren't."

Her lucky break came when she was spotted by a photographer while working in a parachute factory during the Second World War. The pictures turned her into a much sought-after cover girl, and the bleached blonde bombshell was born.

Within a year of appearing on her first magazine cover in 1946, she'd been on 33 more, including Playboy, who made her their first ever centrefold in 1949.

She was noticed by a Twentieth Century Fox talent scout, changed her name, and the rest is history. Niagara and Gentlemen Prefer Blondes launched her as a sex symbol superstar, and her portrayal of Sugar Kane in Billy Wilder's Some Like it Hot won her a Golden Globe.

The film, which recently topped the polls in the American Film Institute's list of the greatest ever comedies, is "sexy, sassy, funny and frivolous", according to the British Film Institute, which believes it may have been Monroe's ultimate performance.

"Playing the mesmeric musician, Sugar Kane, Monroe never looked better and oozes the easy charm that ensnared the hearts of a million men."

Wilder famously said of working with her: "I've discussed this with my doctor and my psychiatrist, and they tell me I'm too old and too rich to go through this again."

Actress Juliette Lewis, who starred as a Marilyn Monroe impersonator in the film Room to Rent says: "I think Marilyn Monroe was a very intelligent person who knew what she was doing. She knew her comic skills. But, socially, she did put on the lip quiver and that dizzy blonde act.

"You don't have to engage in an intellectual way with people, you can hide behind this dizzy veneer and it's also very disarming to people around you. I connected to the champagne buzz."

But the BFI suggests another reason for our enduring affection. She was the first real victim of stardom and its destructive qualities, which made her appear both elusive and human at the same time.

"The legend endures today more strongly than ever. She appeared to undulate rather than walk; she exuded sensuality. Yet she had a wholesome shyness. While she understood, from a very young age, her effect on men, and craved their approval, she was less certain of her own talents," it says.

"As with many stars, there was a widespread feeling of loss when she died. Even if stars rarely seem to be the products of stable childhoods, upon Monroe's death, the public became aware of stardom's destructive potential."

Rachael Crofts