The lead French investigator into Princess Diana’s death found ‘little clues’ at the scene of the tragic  car crash in Paris, including ‘tiny pearls’ belonging to the royal.

Monteil said she was ‘obsessed’ with finding even the tiniest evidence, like the pearls, because it was all ‘important’ when probing what happened in the Pont de l’Alma tunnel on August 31, 1997.

The officer’s testimony is featured in episode one of Investigating Diana: Death In Paris, a documentary beginning tonight on Channel 4 to mark the 25th anniversary of the tragedy.

The four-part series examines two police investigations into the royal’s death, as well as the conspiracy theories alleging her death was staged by other British monarchs.

French police chief chief Martine Monteil (pictured in November 2018) said investigators ‘started to find these little clues’ at the crash site where Princess Diana died

French police chief chief Martine Monteil (pictured in November 2018) said investigators ‘started to find these little clues’ at the crash site where Princess Diana died

The lead investigator into Princess Diana’s death found ‘little clues’ at the scene of the tragic car crash in Paris, including ‘tiny pearls’ belonging to the royal. The Princess of Wales is pictured at the Red Cross headquarters in Washington DC in June 1997

The lead investigator into Princess Diana’s death found ‘little clues’ at the scene of the tragic car crash in Paris, including ‘tiny pearls’ belonging to the royal. The Princess of Wales is pictured at the Red Cross headquarters in Washington DC in June 1997

Brigade Criminelle chief Martine Monteil, who was first to arrive on the scene, recalled how they found ‘tiny pearls,’ broken car bits, evidence of braking and traces of paint on the vehicle carrying Diana and her lover, Dodi Fayed

Brigade Criminelle chief Martine Monteil, who was first to arrive on the scene, recalled how they found ‘tiny pearls,’ broken car bits, evidence of braking and traces of paint on the vehicle carrying Diana and her lover, Dodi Fayed

The wreckage of Princess Diana’s car is lifted on a truck in the Alma tunnel of Paris on August 31, 1997. The royal died a few hours after the crash at Paris hospital of La Pitie-Salpetriere of her injuries

The wreckage of Princess Diana’s car is lifted on a truck in the Alma tunnel of Paris on August 31, 1997. The royal died a few hours after the crash at Paris hospital of La Pitie-Salpetriere of her injuries

The first instalment of the upcoming docuseries follows the immediate aftermath of the crash and investigation led by France’s elite Brigade Criminelle.

‘We started to find these little clues,’ Monteil said of the initial crash scene, in an exclusive clip of the interview provided to Mail Online.

‘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.’

Monteil added: ‘I even found some tiny pearls. They belonged to the Princess.’

French detectives reportedly dove straight into the investigation, reconstructing the car’s route and chasing every possible lead. They also were forced to manoeuvre between ‘unreliable witnesses and fallible memories.’

French detectives reportedly dove straight into the investigation, reconstructing the car’s route and chasing every possible lead

Brigade Criminelle officer Eric Gigou shared how police took the paparazzi into custody and used their photos to piece together the moments before and after the crash.

‘We reconstructed the route they took,’ he explained. ‘Tried to discover all the witnesses, people who might have crossed paths with the car, seen motorcycles, seen something.

‘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.’

Investigators note how they also had to block out ‘countless conspiracy theories’ that sprung up – both in the press and online – almost immediately after the crash.

Monteil and Gigou were among dozens of police officers, medical professionals, firemen and eye witnesses interviewed for the four-part series.

Investigators also had to block out ‘countless conspiracy theories’ that sprung up – both in the press and online – almost immediately after the crash. Princess Diana is pictured sitting on a step at her home, Highgrove House, in Doughton, Gloucestershire on July 18, 1986

Investigators also had to block out ‘countless conspiracy theories’ that sprung up – both in the press and online – almost immediately after the crash. Princess Diana is pictured sitting on a step at her home, Highgrove House, in Doughton, Gloucestershire on July 18, 1986