NEW evidence has emerged to crack open a vintage whodunnit that has fascinated wine connoisseurs for more than 20 years — and is now at the centre of an international investigation into the trade in fine wines.

A legendary cache of claret purportedly owned by Thomas Jefferson, the third US president, is almost certainly fake.

Court documents obtained by The Sunday Times show that Christie’s, the London auction house, “authenticated” its origin despite warnings that it could never have belonged to Jefferson. Four bottles of the wine were sold to an American multi-millionaire for £200,000. Without the Jefferson link they would not have been worth more than £2,000 each.

They are now part of a wider FBI investigation into the £100m-a-year international fine wine trade. It has subpoenaed both Christie’s and a second auction house, Sotheby’s, to reveal details of their antique wine sales. The affair has become so fiercely contested that French nuclear scientists and academics who examined the Turin shroud have been asked to evaluate the Jefferson bottles.

One expert said: “These expensive bottles of wine are the guys’ version of the Hermãs handbag.” Yet at least one in 20 vintage wine bottles is believed to be a modern forgery.

Bill Koch, a multi-millionaire who bought four of the Jefferson bottles in 1988, is pursuing a legal action in New York against Hardy Rodenstock, a German wine merchant who claims to have found the 18th-century Bordeaux wine. Koch’s writ in a New York court says: “Rodenstock is charming and debonair. He is also a con artist.”

The wine was authenticated by Michael Broadbent, then head of Christie’s wine department in London. Broadbent, now 79 and still a director of the auction house, admits that he was a frequent guest at marathon wine tastings held by Rodenstock, and attended by politicians and international footballers.

Monticello, Jefferson’s estate in Virginia, warned three months before the sale that there was no evidence that the wine had belonged to Jefferson.

Rodenstock has repeatedly claimed that the wine was found in a walled-up cellar in Paris in 1985 but has refused to reveal the exact location. He insists that the wine is “absolutely genuine and anyone who drinks it is drinking history”.

The new evidence shows that Christie’s told another buyer a different story: that the wine had been looted by a German panzer division during the war. It is also makes clear that initials purportedly carved on the bottles by Jefferson are the modern product of an electric engraving tool.

Jefferson, the principal author of the Declaration of Independence, was America’s first ambassador to France before succeeding John Adams as president. He visited the Bordeaux vineyards, kept copious notes of the wine he ordered and was moved to write: “Good wine is a daily necessity for me.”

While the wine sold as his may be from the right period, it includes vintages not mentioned by Jefferson in his cellar records.

The biggest doubts, however, are over the letters “Th.J” — supposedly Jefferson’s initials — engraved on each of the bottles. Jefferson’s estate says he never engraved his wine bottles and whenever he did use his initials he wrote them as “Th:J”.

Richard Marston, a former Scotland Yard detective, has unearthed evidence that suggests Rodenstock made up different stories about the origin of the wine. He traced another buyer, Basil Shiblaq, a London-based financier.

Shiblaq, who bought a 1784 Chateau d’Yquem bottle of wine engraved with Th.J at a Christie’s auction in 1986, said that Christie’s had told him that the wine was found by Rodenstock’s father. He was supposedly a general in a German panzer division that occupied Paris during the second world war.

In an affidavit filed in New York, Marston states that Shiblaq told him that the story that the bottles were found behind a walled-up cellar “was fabricated to try to avoid the bottles being claimed as looted artefacts by the descendants of the original owners”.

The FBI is likely to interview Marston as a witness in its wider investigation into the wine trade. During the 1990s he served asa British vice-consul in Miami and was in charge of a joint FBI and Scotland Yard task force to combat economic crime in the Caribbean.

Rodenstock, whose father was in charge of German troop trains on the Russian front and was not in Paris during the war, said last week that he had done everything he could to prove the authenticity of the bottles.

“It may well be that the people who have sold me these bottles have had them reengraved over the old original engravings to make them more legible,” he said.

At his home in Old Sodbury in Gloucestershire, Broadbent said: “It is a load of rubbish to say that this is Nazi loot but I am too exhausted to discuss it further.”

Christie’s said: “We will not sell any lot that we know or have reason to believe is inauthentic or counterfeit.”

Malcolm Forbes, the billionaire who died in 1990, paid £80,000 for a 1787 bottle of Chateau Lafite from the Jefferson hoard at a Christie’s auction in 1985.

The cork subsequently dried out in its display case and dropped into the bottle. Forbes’s comment at the time sums up the feelings of many of those connected with the wine: “I wish Jefferson had bloody drunk the thing.”

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