Rodenstock had adopted his new identity at about the time he met York, the investigators said, and told her that he was part of the famous Rodenstock family. It was while he was with York that he first became interested in wine. She didn’t share his devotion to the hobby. She remembered placing a bowl of potato salad in his air-conditioned wine cellar one day, to keep it cool. “Rodenstock just flipped out,” she said.

Rodenstock was known for his discerning nose and his ability to identify wines in blind tastings. Elroy wondered whether he might possess the skills of a mixer, the type of expert that vineyards employ to achieve a precise blend of grapes. There are no scientific tests that can reliably determine the grape varietals in a bottle of wine, and Elroy speculated that Rodenstock might have concocted forgeries by mixing various wines—and even a dash of port, as forgers have been known to do—in order to create a cocktail that tasted like the real thing. Pursuing these suspicions, Elroy’s team of investigators asked several people they interviewed whether they had any recollection of Rodenstock’s having a laboratory where counterfeits could be made. Then, last October, a German named Andreas Klein approached Koch’s team and said that Rodenstock had lived for several years in an apartment owned by his family. The two had quarrelled over Klein’s desire to add an apartment above Rodenstock’s, and ended up in court. In 2004, after Rodenstock abandoned the apartment, Klein entered his former tenant’s cellar and discovered a collection of empty bottles and a stack of apparently new wine labels. In response to these claims, Rodenstock has initiated legal proceedings against Klein.

There are two types of wine counterfeiters: those who do not tamper with what is inside the bottle and those who do. Because the price of a great vintage of fine wine often dwarfs the price of an indifferent one, many forgers will start with a genuine bottle of, say, 1980 Pétrus and simply replace the label with one from 1982. (The ’82 vintage is especially coveted and expensive.) With a good scanner and a color printer, labels are easy to replicate—one former auctioneer I spoke with called it “desktop publishing.” The cork in the bottle is marked with the year, but forgers sometimes scratch away the last digit, assuming that the buyer won’t notice. Moreover, because corks tend to deteriorate after decades in the bottle, some vineyards offer a recorking service, so a bottle with a newer cork might not immediately arouse suspicion. In any event, the cork is generally concealed by the foil capsule until the buyer opens the bottle.

The forger’s greatest advantage is that many buyers wait years before opening their fraudulent bottles, if they open them at all. Bill Koch told me that he owns wine that he has no intention of ever drinking. He collects bottles from certain vineyards almost as if they were baseball cards, aiming to complete a set. “I just want a hundred and fifty years of Lafite on the wall,” he said. He would hesitate before consuming the harder-to-come-by vintages, because to do so would render the set incomplete, and also because the rarest old wines often come not from the best vintages but from the worst. Historically, when good vintages were produced, collectors would lay them down to see how they would age, Koch explained. But when renowned vineyards produced mediocre vintages people would drink them soon after they were bottled, making the vintage scarce. When I wondered why he would buy old wines that he never intended to drink, Koch shrugged. “I’m never going to shoot Custer’s rifle,” he said.

The second great advantage for wine forgers is that when collectors do open fraudulent bottles they often lack the experience and acute sense of taste to know that they have been defrauded. To begin with, even genuine old wines vary enormously from bottle to bottle. “It’s a living organism,” Sotheby’s Serena Sutcliffe told me. “It moves, it changes, it evolves—and once you’re into wines that are forty, fifty, sixty years old, even if the bottles are stored side by side in similar conditions, you will get big differences between bottles.”

Studies suggest that the experience of smelling and tasting wine is extremely susceptible to interference from the cognitive parts of the brain. Several years ago, Frédéric Brochet, a Ph.D. student in oenology at the University of Bordeaux, did a study in which he served fifty-seven participants a midrange red Bordeaux from a bottle with a label indicating that it was a modest vin de table. A week later, he served the same wine to the same subjects but this time poured from a bottle indicating that the wine was a grand cru. Whereas the tasters found the wine from the first bottle “simple,” “unbalanced,” and “weak,” they found the wine from the second “complex,” “balanced,” and “full.” Brochet argues that our “perceptive expectation” arising from the label often governs our experience of a wine, overriding our actual sensory response to whatever is in the bottle.

Thus there is a bolder kind of forger who actually substitutes one type of wine for another. He often works with genuine bottles bearing genuine labels, obtaining empties from restaurants or antique shops, filling them with another type—or types—of wine, and replacing the cork and the capsule, assuming that the status-conscious buyer will never taste the difference. And, in many cases, this assumption is right. Sutcliffe believes that the vast majority of fake wines are happily enjoyed. Rajat Parr, a prominent wine director who oversees restaurants in Las Vegas, told me that several years ago some of his customers ordered a bottle of 1982 Pétrus, which can sell in restaurants for as much as six thousand dollars. The party finished the bottle and ordered a second. But the second bottle tasted noticeably different, so they sent it back. The staff apologetically produced a third bottle, which the diners consumed with pleasure. Parr closely examined the three bottles and discovered the problem with the second one: it was genuine.

If the Th.J. bottles were counterfeit, the question facing Jim Elroy was whether someone else’s genuine eighteenth-century bottles had been passed off as Thomas Jefferson’s or whether the wine had actually been adulterated. The fact that Broadbent and other connoisseurs had tasted several Jefferson bottles and declared them authentic seemed to suggest that the wine in the bottles was the real thing. Jancis Robinson, another Master of Wine and the wine columnist for the Financial Times, had attended the 1998 Yquem tasting, and found the two Th.J. bottles “convincingly old,” slightly moldy initially, but then, as “the miracle of great old wine began to work,” opening up, with the 1784 giving off a “feminine fragrance of roses” and the 1787 “autumnal aromas of burnt sugar and undergrowth.”

But Brochet told me that, in tastings, experts are more susceptible than average drinkers to interference from their own experience and presumptions. And these endorsements seem to be disputed by the scientific test commissioned by Hans-Peter Frericks, which found that nearly half of the wine in his 1787 Lafitte dated to sometime after 1962. Following Frericks’s test, Rodenstock had commissioned his own, on another bottle of 1787 Lafitte, from Dr. Georges Bonani, a Zurich scientist. Bonani carbon-dated the wine and determined that no wine in the bottle dated to 1962 or later, thus contradicting the specific finding of Frericks’s study. Rodenstock frequently referred to Bonani’s results as “conclusive” in their authentication of the bottle. But it seems difficult to consider any of these tests truly conclusive. For one thing, the different tests were conducted on different bottles, and it seems rash to extrapolate from the results of one bottle anything about the authenticity of the others. Further, carbon dating can’t provide a reliable determination of the age of wines bottled during the eighteenth and nineteenth centuries, and an examination of Bonani’s lab report reveals that his findings reflected a considerable margin of error. While the test might have ruled out the presence of late-twentieth-century wine, it did not provide absolute proof that the wine dated to 1787. “The test says only that the wine is from somewhere between 1673 and 1945,” Bonani wrote in a recent e-mail.