The first time since 1997.

Police in France have spoken about the car crash that killed Princess Diana in 1997 for the first time since her death. Opening up about her death in the new Channel 4 documentary, Investigating Diana: Death In Paris, detectives who worked on the case nearly 25 years ago are openly talking about the tragedy. Speaking in the documentary about her passing, Eric Gigou from the Brigade Criminelle explained that the route Diana took that night has now been "reconstructed" as a way for them to reexamine what happened. "We reconstructed the route they took, tried to discover all the witnesses, anyone who could have seen or heard anything near or far, people who might have crossed paths with the car, seen motor cycles, seen something in the minutes or seconds before the crash, perhaps at the moment of the impact or after the impact," he said. "For us it is a race against time from the moment we were given the case, because human memory is volatile and over time memories fade." The episode he appeared in is the first of a four part documentary that tells the story of Henri Paul, the driver of the car the Princess of Wales was travelling in at the time. It spoke about the allegations that he was over the limit when the crash occurred. Going on to discuss the different newspaper allegations at the time, Gigou said: "In France, our investigations are secret, nothing is revealed to the press. Every day there were articles with pseudo-revelations, some magazines were living off these 'scoops'. "When you look at the CCTV from the Ritz, Mr Paul is behaving normally. He does not stagger, he seems normal. If Henri Paul had stumbled or been incoherent he would never have got behind the wheel. Did someone ask Henri to drive faster, I don't know. No one knows." Also speaking in the documentary was police chief Martine Monteil who addressed the "pearls" at the scene of the crash which were believed to have belonged to Princess Diana. Being one of the first to arrive at the scene, she explained that she had been looking for the tiniest details. "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. "I even found some tiny pearls. They belonged to the Princess." Diana, along with the driver Henri Paul and her boyfriend Dodi Fayed, was killed in the crash in Paris at the age of 36 in August 1997. The second instalment of Investigating Diana: Death In Paris is set to air on Channel 4 tonight at 9pm.