Martine Monteil, the French police chief who oversaw the investigation into the death of Princess Diana in 1997, says in a new documentary series she found “tiny pearls” at the crash scene that “belonged to the princess.”

Ahead of the 25th anniversary of the high-speed car crash in Paris that killed Diana along with her boyfriend, Dodi Fayed, and driver Henri Paul, British broadcaster Channel 4 is airing Investigating Diana: Death in Paris, which examines the incident and its potential causes.

Following the crash in the Pont de l’Alma tunnel in the early morning hours of August 31, 1997, two inquests were held. One took place in France during the weeks immediately after the incident, and the second was conducted in Britain in 2008.

Princess Diana on June 16, 1995, and the car (inset) in which she was riding at the time of her death on August 31, 1997. A former police chief describes finding “little clues” around the… More Tim Graham Photo Library via Getty Images/PIERRE BOUSSEL/AFP via Getty Images
Speaking to the documentary’s makers, Monteil recalled how she was one of the first police officers to visit the crash site, which was immediately treated as a crime scene. Members of the paparazzi who had pursued the princess’s car at high speeds from the Ritz hotel were arrested on suspicion of causing the accident.

At the crime scene in the Pont de l’Alma tunnel, which was closed while police inspected the site, Monteil recalled finding clues littered about, including debris from a second car involved in the accident.

“We started to find these little clues,” she said. “We saw signs of braking. Pieces of red light from another car. On the side of the car were traces of paint. I was obsessed with finding things because it’s important.”

Among these small clues, Monteil came across some items that belonged to Diana. “I even found some tiny ,” she said. “They belonged to the princess.”

The French inquest ruled that Diana’s death was “accidental” and that Paul, who was acting head of security at the Ritz, had a blood alcohol level over the level permitted to drive. Also, six members of the paparazzi were charged with manslaughter for their role in pursuing the car, although the charges were later dropped.

The 2008 British inquest ruled that the princess was unlawfully killed owing to the “grossly negligent driving of the following vehicles [the paparazzi] and of the Mercedes driver Henri Paul.”

Three photographers were tried after being charged with invasion of privacy when it was discovered they had taken photographs through an open door of the Mercedes after the crash. The photographs were seized by French police. The photographers were acquitted in 2003.

Those photographs assisted investigators in putting together a comprehensive timeline of the crash, including who was near the princess’s car before and after impact.

Princess Diana and Dodi Fayed, in the back seat, and bodyguard Trevor Rees-Jones and driver Henri Paul leave the Ritz hotel in Paris before their car crashed in the Pont de l’Alma tunnel on August… More Jacques Langevin/scottbaker-inquests.gov.uk via Getty Images
Eric Gigou, Monteil’s colleague at the Brigade Criminelle, also appears in the docuseries. He told OK! magazine, “We reconstructed the route they took. Tried to discover all the witnesses, people who might have crossed paths with the car, seen motorcycles, seen something.”

He continued, “For us, it’s a race against time that started the moment we were given the case, because human memory is volatile and over time memories fade. The paparazzi are in custody. From their photos, we could see the last minutes before the accident. We could identify the people around the vehicle in the seconds afterwards.”

The series also explores several high-profile conspiracy theories surrounding the crash that emerged over the following decade. Among them are claims that a blinding light had been deployed to disorientate Paul and that British intelligence operatives were shadowing Diana during her Paris stay.

These conspiracy theories were thoroughly examined as part of the 2008 British inquiry, Operation Paget. Its report said none of the claims investigated were found to have been a cause of the accident.