An investigator who said he was acting for police after Princess Diana's fatal crash was working for Mohamed Al Fayed, an inquest into her death has heard.
Princess Diana died in a car crash in a Paris tunnel in August 1997
Michel Kerbois tried to buy a battered white Fiat Uno previously owned by photographer James Andanson.
Mr Al Fayed believes the vehicle may be the mystery Fiat which collided with Diana's car moments before the crash.
The Harrods owner claims Mr Andanson, who has since died, was involved in an MI6 in a plot to murder the princess.
The vehicle had been bought by car dealer Jean-Francois Langlois from Mr Andanson, who was found dead in controversial circumstances in 2000.
It was purchased nine weeks after the crash in Paris in August 1997 in which Diana, Mr Al Fayed's son Dodi, who was her boyfriend, and their driver Henri Paul died.
The court has heard that police examined the Fiat Uno but ruled it out of involvement in the crash.
Mr Langlois described how Mr Andanson came to him to sell the car for scrap on 4 November, 1997.
He told the High Court hearing via videolink from Paris that Mr Kerbois called at his garage saying he was acting on behalf of the police.
He said: "He knew exactly what kind of vehicle I had, that the Fiat Uno was there and actually he even suggested that he could buy it."
Mr Langlois refused to let him take away the car, which was later seized by police, because he did not think it was roadworthy.
The car dealer told the jury that he later became aware that Mr Kerbois was an inquiry agent paid by Mr Al Fayed.
The court also heard from former Paris Match journalist Christophe Lafaille who arranged to meet Mr Andanson for lunch on 4 May 2000, only to find he had died.
Mr Andanson's burned remains were discovered in a car in a forest in the south of France.
Mr Lafaille said he had come to the same conclusion as the police, that Mr Andanson had committed suicide.
The hearing continues.