Maybe she staged her own death and is living it up in a secret tropical hideaway. Maybe Henri Paul, the chauffeur on the fateful night, was an agent for MI6, Britain's equivalent of the CIA, hired by the royal family to kill her (and himself -- oops!) as their Mercedes sped through a Parisian underpass.
Or, as the exasperated columnist Simon Hoggart of The Guardian wrote on Thursday, maybe Diana, Princess of Wales, died on Aug. 31, 1997, because "Prince Charles, together with various gay courtiers, shot at the car from a stealth helicopter just as it entered the tunnel."
You could speculate endlessly about Diana's death -- and 27 percent of the British public, by one poll, believes that it was murder -- but until last week you would have been hard-pressed to find a responsible public figure willing to entertain any of the conspiracy theories.
That all changed Tuesday. In an odd turn of events, Michael Burgess, the man presiding over the British inquests into the deaths of Diana and the boyfriend who died with her, Emad Mohamed al-Fayed, mysteriously refused to dismiss the murder hypotheses.
"I am aware that there is speculation that these deaths were not the result of a sad, but relatively straightforward, road traffic accident in Paris," Burgess said, before directing the Metropolitan Police to look into the matter and report back.
Burgess was hardly announcing a Warren Commission for modern times, but his astonishing request heartened proponents of the murder theory, as well as throwing a small crumb of legitimacy, perhaps, to those who believe that the 1969 lunar landing took place on a Hollywood back lot and that Elvis lives (with Diana, maybe!) in a Florida trailer park.
As far as Diana goes, most nonaccident theories have been discredited. In 1999, the French authorities concluded that the accident took place because Paul, the driver, was drunk and speeding out of control. On Thursday, Jean-Claude Mules, a senior police officer in that investigation, told The Daily Telegraph that the continued rumors of murder and cover-up were "absurd" and that his team had already looked into the various "hypotheses, theories and allegations" swirling around the accident.
Yet the rumors persist, like niggling gnats. Some people might find them good conversation pieces, as ice-breaking as the English weather; others might be X-Files-style enthusiasts, seeing second gunmen lurking behind every shrub and plots behind every unexplained detail; and others, said Cary Cooper, a professor of psychology and health at Lancaster University, simply take emotional comfort from them.
"People need explanations," Cooper said in an interview. "Diana was attractive, young and a celebrity, and quite a lot of people can't understand it when a young person dies. They have to find some kind of theory, some kind of explanation behind it."
Cooper said that some people find that believing in all-powerful government agencies, even secret and ruthless ones, is more palatable than accepting that death is unpredictable.
"If things can just happen to you randomly, it means you are vulnerable," he said. "We'd rather think there was something behind it, because then we could, maybe, control it. If we can find someone who killed Kennedy, maybe we can find a way so that it doesn't happen again, not just to other Kennedys, but to other people."