The moon landing was shot on a Hollywood back lot. There was a second shooter on the grassy knoll when John F. Kennedy was killed. And the Illuminati secretly controls the world.
Some of the greatest and most tragic events of the 20th century have long been fodder for conspiracy theorists and lodged themselves firmly in the public consciousness. But in the hours and days after August 31, 1997, another theory took hold: The death of Diana, Princess of Wales, in the Pont d'Alma tunnel in Paris was murder.
The biggest proponent of this thinking (for many years) was Mohammed Al-Fayed, the father of Dodi Al-Fayed who was killed instantly when the speeding black Mercedes limo crashed into the 13th pillar. For years Al-Fayed senior waged a legal and PR war arguing that dark forces inside the British establishment and the security services had conspired to kill the Princess of Wales and Dodi. The official British inquest found the "gross negligence" of driver Henri Paul caused the crash.
However, more than 20 years since that fateful night, there are a number of strange, unanswered issues that remain.
AN ENGAGEMENT AND A PREGNANCY
Even though they had been dating for less than a month, one of the biggest lingering questions hanging over this period of time is just how serious was Diana about Dodi? Mohammed Al-Fayed has previously claimed that on the evening of August 30, the couple had called him and announced they were engaged and she was pregnant.
Reporters Tom Sancton and Scott MacLeod wrote in their book Death of a Princess: "For the mother of the future king of England to bear the child of a Muslim Arab, a child who would be the half sibling of the heir to the throne, would be embarrassing in the eyes of the royal family and the ruling establishment."
The afternoon of August 30, Dodi had a 6.30pm appointment to pick up a diamond ring at the Repossi jewellery store just outside the Ritz Hotel. Some have argued the new couple had chosen the ring the week before while they were in Monte Carlo.
However, the royal's close circle has long contended the Diana/Dodi pairing was a summer fling and nothing more.
The day before they left for Paris, Diana rang her PA Jackie Allen. "She said how much she was looking forward to getting home, and there was something in the way she said it that gave me the impression she was actually saying, 'I'm bored with this now'," Ms Allen told the Daily Mail.
"It's very much a personal view, but I don't think she would have seen Dodi again once she got back."
While it might not have been a long-term romance, was Diana pregnant?
Most likely not. Dr Robert Chapman, who conducted the British autopsy of Diana, said a "visual inspection" indicated she was "not pregnant".
However, Dr Alan Schiller, professor and chair of pathology at Mount Sinai School of Medicine in New York, told Vanity Fair: "This is ridiculous — you just don't do that. It is impossible to see a one-to-three-week-old foetus with the naked eye. Even at six weeks, it would be only four or five millimetres long."
That said, earlier in the month of August, Diana had gone on a cruise in Greece with close friend Rosa Monckton who told the British inquest the Princess had her period while they were away, thus making it impossible for her to be pregnant when she died.
THE WHITE FIAT UNO
Analysis of the Mercedes later found traces of paint that pointed to it making brief contact with a white Fiat Uno.
Several weeks after the crash, two witnesses — Georges and Sabine Dauzonne — came forward and said they had seen a white Fiat Uno shortly after the crash. They claimed there was a large dog wearing a red bandana in the back seat and the driver had been driving erratically.
French authorities then examined more than 5000 vehicles but never conclusively found the car.
In November of that year, French police arrested Thanh Le Van, a then part-time security guard who had a similar car. The vehicle had been resprayed and changed its bumper shortly after the crash. Vanity Fair reports "Chemical analysis showed that the original paint was 'compatible with the white traces seen on the Mercedes'."
However, Mr Le Van had an alibi — he'd been working at the time — and was later ruled out of the investigation.
THE PAPARAZZO'S DEATH
James Andanson was one of the paparazzi who had been photographing Dodi and Diana during their Mediterranean holiday. In 1998, it became apparent Andanson also owned a white Fiat Uno.
It had been sold a few months after the crash but police found the car. According to reports, the left rear light had been changed but the "the original paint chemically matched the paint of the mystery car". However, Andanson's vehicle had apparently been repainted prior to the August smash and showed no evidence it had been involved in the collision.
In 2000, Andanson's body was discovered in his burnt-out car.
"It was clearly no ordinary affair," said Alain Durand, then the state prosecutor for the area. "The circumstances of the death were very peculiar. As soon as I learned the identity of James Andanson, I told the investigating magistrate to do the maximum because it was an affair that could have links to the death of Diana."
Andanson's death was later ruled as a suicide after investigators found what they believed was a "virtual suicide note".
From the time the Mercedes collided with the pillar to the time Diana arrived at the University Hospitals Pitié Salpêtrière, one hour and 42 minutes had elapsed. While an ambulance arrived on the scene within minutes, French emergency medicine dictates patients be stabilised and then transported.
While Diana's injuries were initially thought to be a broken leg and some abrasions, the severity of the internal toll soon became apparent with her experiencing a cardiac arrest while in the tunnel and then later while en route to the hospital.
Could she have survived if Parisian ambulance crews had whisked her straight to emergency?
Doctors later concluded she had experienced a heart injury that would have proven fatal, even if she had been in hospital.
HENRI PAUL'S AUTOPSY
One of the lingering question marks concerns driver Henri Paul's blood samples. During his autopsy, blood and tissue samples were taken and went to two different labs. His blood alcohol level was three times the legal French limit and he had "therapeutic" levels of prescription drugs — Tiapridal and Prozac — in his system. These levels of drugs and alcohol reportedly should have impaired him such that those around him would have noticed. But people who had been with Paul earlier that night did not notice any issues.
The other issue was the CO2 level in his blood, registering at 20.7 per cent. At that level, he should have been experiencing dizziness, confusion and headaches.
Days later, new blood, hair, and tissue samples were taken with the entire procedure photographed. The same blood alcohol level was discovered but the CO2 levels were a (still high) 12.8 per cent.
Investigators struggled to explain the levels of CO2, questioning whether the samples being taken from different places in the body could explain things. (Nor could Paul's smoking. His apartment was also checked for possible leaks.)
Pathologists from the University of Lausanne concluded, "Of all the hypotheses that we have considered (to explain the carbon monoxide levels), an error in the blood samples seems the most plausible."
THE CIA FILE
Mohammed Al-Fayed fought in the courts for access to the CIA's 1056-page file about the Princess but to no avail, with the Defence Department stating a review showed no substance of events connected to her death.
Assertions that MI6 or some other secretive agency had plotted to kill Diana sound like the stuff of a Le Carre Novel.
After his death, Mr Paul's bank account was found to contain hundreds of thousands of dollars, yet he earned only about $50,000 a year. French investigators later argued he had acquired that much cash through tips from patrons at the Ritz.
While the official inquest concluded Mr Paul's "gross negligence" was to blame, writer Tom Sancton has suggested there are subtle indications of "possible intelligence activity in connection with the case".
He says a British photographer told another journalist a contact in MI6 had said "stay away from Paris this weekend".