It’s been nearly 20 years since Princess Diana‘s death — and royal fans are still posing fascinating questions about the car crash that killed the People’s Princess in August 1997. On Monday, July 31, a new special titled Princess Diana: Tragedy or Treason aired on TLC, leading many people to wonder if Diana was wearing a seatbelt when she died in an accident in Paris’ Pont de l’Alma tunnel.

Tragically, Diana was not wearing her seatbelt while sitting in the back seat of a black Mercedes-Benz sedan at the time of her death. Two other people — Diana’s boyfriend Dodi Fayed and her driver, Henri Paul — were killed in the fatal accident. Miraculously, the royal’s longtime bodyguard, Trevor Rees-Jones, survived the crash.

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In 1997, French authorities investigating the wreck later confirmed Trevor was the only passenger wearing a seatbelt in the vehicle. He reportedly did not fasten his safety belt when he first got in the car but Henri’s reckless driving and the Mercedes’ increasing speed — the driver was trying to flee from paparazzi chasing Diana — led him to put on his seatbelt right before the vehicle crashed in the Pont de l’Alma tunnel.

Following the fatal crash, a CNN study using computer simulation technology sadly revealed Diana could have survived the accident if she was wearing a safety belt in the car. “Without seat belts, both the head and chest of a person sitting in the right rear seat — where Diana sat — would have hit the back of the front seat with great force,” the research found. If she had been restrained by a seatbelt, “those are both very survivable kinds of impacts,” computer crash analyst David Renfroe said at the time, adding that Diana might have suffered, at worst, some broken ribs or a broken sternum, nothing life threatening, if she had buckled her seatbelt.

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In the new TLC special Princess Diana: Tragedy or Treason, former Daily Mirror News Director David Leigh suggested that if Diana had had the royal family’s security personnel with her — she lost their protection when she divorced Prince Charles in 1996 — at the time of her death, that they would have told her to fasten her seatbelt in the car. “I’m sure that if she was with royal protection officers, they would have insisted, even though she was Princess Diana, please ma’am put your safety belt on,” Leigh said.

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Diana wearing her seatbelt during a une 1995 car ride. (Photo Credit: Getty Images)

“There are people who say, that possibly if she had had her seatbelt on, it might have saved her,” Royal Historian Kate Williams said in the documentary. “I guarantee you, people get in their car [today] and they fasten their seatbelt and they think, ‘Diana would be alive today if she had done what I just did.’ It may be one of the great legacies that she has left the world, something as simple as buckle your seatbelt because [her sons, Prince William and Prince Harry], would have grown up with their mother,” broadcast journalist Deborah Norville added.

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