The forensic pathologist who worked on Princess Diana’s inquest has a clear message for conspiracy theorists — they’re wrong.

Dr. Richard Shepherd, one of Britain’s leading forensic pathologists, has performed thousands of autopsies during his long career, including work on some of the world’s most high-profile cases. His investigations have included victims of 9/11, the 7/7 London bombings, the Hungerford massacre, the sinking of the Marchioness, and the Bali bombings.

But the one case he’s asked about more than any other is the death of Diana, Princess of Wales.

The expert, who has examined more than 23,000 bodies, was brought in as a consultant during the inquiry into her death to review the autopsy and give expert evidence.

Recalling the experience, Dr. Shepherd told Tyla: “It’s like standing in the middle of a thunderstorm. Everything’s coming down at you — flashes, bangs — but it was very interesting. We had a critical job to do.”

Princess Diana died in August 1997, aged just 36, following a car crash in Paris. She was travelling through the Pont de l’Alma tunnel with Egyptian film producer Dodi Fayed when their Mercedes-Benz S280 collided at high speed. Dodi’s bodyguard, Trevor Rees-Jones, was also in the vehicle, driven by Henri Paul — later found to have been intoxicated by alcohol and under the effects of prescription drugs.

Although Diana was initially conscious after the crash, she went into cardiac arrest soon after. During surgery, doctors discovered a small tear in a vital pulmonary vein — the injury that ultimately caused her death.