For some it is a case straight out of the X-Files. The lives of a beautiful princess and her millionaire boyfriend snuffed out suddenly in a Paris underpass. Tragic car accident or brutal assassination? The plots thicken.
According to conspiracy theories the "so-called facts" about the "accident" do not speak for themselves.
Plausible explanations - the driver of the Mercedes, Henri Paul, was drunk, the car was exceeding 100 m.p.h. - are discounted as "disinformation", leaving everyone from the MI5 to Bill Clinton responsible for the tragic events.
On the Internet a man called Sherman H. Skolnick asserts that "various Western intelligence agencies arranged to assassinate Princess Diana in Paris". He says a car carrying MI5 agents came up behind the Mercedes and hit it "in some way".
Meanwhile, "others" had already arranged for a chemical slick to be put on the roadway within the tunnel. Ahead of this was placed an obstruction of some kind. Diana and Dodi, the theory goes, had no chance of survival.
The motive mooted most often for the "murders" was that the monarchy could not countenance a Muslim stepfather (Dodi) to the heir to the throne (Prince William). In Egypt there are six books on this subject. In one, Queen Elizabeth is alleged to have phoned the British embassy in Paris sometime before the accident and said simply, "kill her".
It all goes downhill from there. A woman calling herself Ru Mills (rumour mill, geddit?) reckons that an organisation known as the New World Order faction had a reason for killing Diana. She cites a bizarre plot in which old royalty would be combined with new money to form a global superpower.
The faction's plan was to marry Diana to an American. As if he didn't have enough woman trouble, Bill Clinton was designated as her future spouse.
The plan went belly-up when Diana told Clinton that she would never marry him. The rejection, says Ms Mill, cost Diana her life.
Another theory contends that business enemies of wealthy Dodi Fayed were involved in his, and Diana's, murder. Still another that her death was a plot on behalf of the world's florists.
While it is to be expected that Cyberspace would foster such tales, the star of the conspiracy theory show continues to be Dodi's father, Mohamed al-Fayed.
Last February he told a newspaper he believed "99.9 per cent" that a conspiracy and not an accident caused the deaths.
In June an ITV documentary, Diana-The Secrets Behind the Crash, raised the possibility that she had been murdered by intelligence services.
Two months earlier, police arrested an Austrian man who had been allegedly trying to extract £15 million from Mohamed al-Fayed in return for documents which implicated British and US intelligence organisations in Diana's death. The CIA denied the existence of such a plot.
Mohamed al-Fayed has reportedly offered £14 million for proof of a conspiracy theory. One of the most amusing theories - did Di really die? - suggests he could be wasting his money.
Some believe that Diana and Dodi (along with JFK, Amelia Earheart and Elvis) faked their deaths and are actually alive on a deserted island somewhere far away from the cursed paparazzi. No doubt the People's Princess is having a right royal laugh at us all this minute. Or maybe not. The truth, as they say, is out there.