Doris Duke was the richest girl in the world; in her twilight years she was also the least predictable. Today a New York court must decide if she really meant to entrust her billion-dollar fortune to her butler. David Usborne reports
While she lived, Doris Duke was breathing proof that money cannot buy happiness. The American tobacco heiress, once known as the "Richest Girl in the World", who hobnobbed with princes, presidents and potentates, ended her life in pathetic loneliness and self-pity. And in death she has taken the truism a step further: money - particularly when you are talking a billion dollars of it - can buy only trouble and destruction.

Told by her daddy, James Buchanan Duke, on his deathbed in 1925 to "trust no one", she would surely be viewing events since her own demise 18 months ago at the age of 80 with weary cynicism. The estate worth $1.2bn that she left for the creation of the Doris Duke Charitable Foundation is destined to become one of America's largest charitable trusts. Almost inevitably it has become ensnared in a furiously intense legal struggle that is due to take a critical turn in a Manhattan courtroom today.

At the centre of the drama is an Irish immigrant named Bernard Lafferty, who became Miss Duke's butler in 1987 and in her final months was her closest friend and confidant. Six months before her death, Miss Duke altered her will for the third time in four years in Mr Lafferty's favour, making him co-executor as well as trustee of the putative foundation. Two weeks ago a New York judge removed the pony-tailed Mr Lafferty as co-executor, citing his assorted binges in recent months, involving both alcohol and, more seriously, hundreds of thousands of the estate's dollars.

The suspension of Mr Lafferty, which is accompanied by dark allegations that he and some of Miss Duke's doctors acted to speed her death with doses of morphine, is due to be reviewed and possibly confirmed by an appeals court this morning.

Labelled in one New York newspaper at the time as "probably the richest mite of humanity in all the world", Doris was born on 22 November 1912 in the Duke mansion on Fifth Avenue. The instant heir to the fortune accumulated by her father through his American Tobacco Company, the maker of Lucky Strike cigarettes, the style in which she would live was never in doubt. "No child of royal blood ever came into the world amid more comfortable surroundings than the daughter of the Dukes," the paper said.

It was in 1931 at Buckingham Palace, fittingly, that Doris Duke began her socialite career. Aged 18, tall and athletic, Doris was one of nine American girls presented to George V and Queen Mary. Thereafter, she would be the object of press fascination, which she claimed to loathe, but of which, equally, she was the prime mover. In her later years, after she had begun to retreat into a circle of servants and advisers, she told a reporter: "I'm not a recluse; I'm a loose wreck".

The list of those she is said to have loved includes Errol Flynn, General George Patton, Hawaiian swimming champion Duke Kahanamoku and, during the war, the British MP Alec Cunningham-Reid. Casual friends included David Niven, Jacqueline Onassis and President and Imelda Marcos, for whom she once posted bail of $5m.

Another friend from the social circuit, Saudi billionaire Adnan Khashoggi, provided the gift that would prompt one of her more famous eccentricities: a pair of camels which she named Princess and Baby. Devoted to animals, she worshipped the camels. She once moved them from the New Jersey Duke farm to the gothic Duke mansion "Rough Point" in Newport, Rhode Island, and was defiant when instructed by local authorities that pasturing of camels on local land was illegal. She had the animals accommodated indoors, forcing servants to protect priceless rugs from their droppings.

It was not a totally empty life. Miss Duke was an accomplished pianist, with a passion for jazz and gospel music, and a good dancer. She was absorbed by orchid farming and today many of the world's most famous varieties bear the Duke name. And throughout her life, she was a generous philanthropist, donating large sums to a multitude of causes.

The extraordinary wealth - there were spreads in Newport, Beverly Hills and Hawaii and a personal Boeing 737 jet - could never protect her from personal disaster. Doris Duke's two marriages were quickly dissolved and in 1940 she gave birth to her only child, a girl who died at once. A second tragic episode occurred in 1966 when she was driving her close friend Eduardo Tirella, an interior designer, to Rough Point and asked him to get out of the car to open the front gate. Inexplicably, her car lurched forward and crushed Tirella against the post, killing him. Miss Duke was cleared of wrongdoing.

Some consolation came to her in 1984, when she met Chandi Heffner, a former follower of the Hare Krishna movement and in many ways a kindred soul. A year later, Miss Duke adopted Heffner as her daughter. It took six years for the relationship to go sour, when Miss Duke disowned Heffner after being advised by a doctor that the woman she had taken to her bosom might have been trying to poison her, an accusation that was never proven.

The start of the final act of her life - and of the tangled legal epilogue that is now playing out - began in the spring of 1991, when she made the first revision of her will, naming one of her physicians, Dr Harry Demopoulos, a nutritionist from Scarsdale, New York, co-executor with the Chemical Bank. In November of that year, she changed her mind again, naming an accountant from Manhattan, Irwin Bloom, the executor.

In April 1992 her years of good health ended when she had a face-lift, performed by a Hollywood surgeon, Dr Harry Glassman, whose wife is the actress Victoria Principal. Two days after the operation, she fell out of bed, broke her hip and had to be hospitalised. While recovering from that she decided, sometime that autumn, that she would like both her knees replaced, apparently because she wanted to dance again. The operation was performed in January 1993, after which she went to her Hawaii home to recuperate. According to her then cook, Colin Shanley, by that stage she "didn't know where she was or what day it was", and was on a regime of painkillers and anti-depressants, and laxatives to keep her thin.

When Miss Duke returned to Los Angeles, doctors found that she was emaciated and intermittently delirious. It was while she was in hospital getting through this episode that the final revision to the will was made. She was able to sign the codicil in Lafferty's favour only with the lawyer present, William Doyle, guiding her hand for her. She died five months later on 28 October 1993 at Falcon's Lair, her Beverly Hills home.

Only in January this year, when the will was in probate in a New York court, did matters begin to unravel. The first to challenge it was Dr Demopoulos, who argued to the court that Miss Duke was mentally incapable when she appointed Lafferty co-executor and trustee. Gradually others joined the chorus of complaint, including Mr Bloom and, most recently, Chemical Bank.

A former nurse at Falcon's Lair, Tammy Payette, filed an affidavit suggesting that Miss Duke's principal physician, Dr Charles Kivowitz, in collusion with Lafferty and Glassman, accelerated her death - indeed murdered her - by deliberately delivering overdoses of morphine to her through an intravenous drip during her last days and hours. Dr Kivowitz has denied the allegation. Ms Payette's credibility, it should be added, has meanwhile been dented by her recent arrest on charges of thieving from her clients, including Miss Duke.

Surrogate Judge Eve Preminger, appointed to approve the will, then asked a former Manhattan District Attorney, Richard Kuh, to compile a report on all the allegations. Completed in April, it offered clear support to the plaintiffs. Kuh gave credence to the morphine overdose scenario and highlighted the extravagant lifestyle adopted by the semi-literate and alcoholic Lafferty.

Among his supposed abuses of the Duke estate was his continued drawing of the $100,000 annual salary he received as butler, when at the same time he stood to receive an annual annuity of $500,000 from the estate and a fee, as executor, of $5m; crashing Miss Duke's Cadillac and buying a new one at the estate's expense; moving into Miss Duke's bedroom suite and refurbishing it at great expense; flying about the country in the Duke 737 jet; and getting legless-drunk, which on one occasion required him to be hospitalised.

Removing Lafferty as co-executor two weeks ago, as well as the US Trust Company appointed by him as the other co-executor, Surrogate Judge Preminger observed of Kuh's findings: "No one could read this sorry record and conclude that the Duke estate has been provided with the loyal and honourable service that the law demands." She also excoriated the US Trust Co, hitherto a venerable money-management institution in New York without a blemish on its reputation - in particular for giving Lafferty a personal loan, an addition to his other income, of $825,000. The implication was that the bank was trying to keep Lafferty sweet, since at any time he could remove it as co-executor.

In the face of shrill protest from both the US Trust Co and Lafferty's lawyers, the New York appellate court last week issued a seven-day injunction against Judge Preminger's decision to suspend Lafferty and the US Trust, though it ordered Lafferty to vacate Miss Duke's bedroom. Both parties were ordered to submit their complaints to the court in writing and await the final decision on whether they are fit to handle the estate - the decision due today.

Still sporting the pony-tail that Miss Duke allegedly asked him to cultivate, Lafferty, who looks the image of dissolution, is choosing to say little of his predicament. But going by a recent quip to a reporter, he seems to have little confidence that he can repel his enemies. "The butler word they like," he observed. "Because the butler always 'did it'."