Britain's most senior policeman is to investigate whether the car crash which killed Princess Diana and Dodi Al Fayed was more than just an accident.
Diana and Dodi died when their car crashed in a Paris underpass
The announcement was made as separate inquests into the couple's deaths were opened and adjourned until 2005.
Coroner Michael Burgess said Sir John Stevens, the Metropolitan Police Commissioner, would look at rumours surrounding the 1997 Paris crash.
Dodi's father, Mohamed Al Fayed, said he hoped "the truth" could now emerge.
On Tuesday it emerged that Paul Burrell, Diana's ex-butler, is to hand the inquest a letter in which she apparently claimed there was a plot to kill her in a crash.
The Daily Mirror claimed the letter appeared to show that Diana believed Prince Charles was behind the plans, although it pointed out the claims were probably "preposterous".
Diana 'not pregnant'
And the Times newspaper is expected to report on Wednesday that a post-mortem examination in 1997 found that Diana was not pregnant at the time of her death.
Conspiracy theorists have speculated Diana was carrying Dodi's child when she died, and that this was a motive for "plots" against her.
But BBC royal correspondent Nicholas Witchell said the Times is expected to quote former royal coroner Dr John Burton as saying he attended the British post-mortem and can categorically say Diana was not pregnant.
The inquests will be the first time the British authorities formally examine the couple's deaths, following a French inquiry which said their driver was drunk and speeding.
Announcing his decision to enlist Sir John Stevens' help, Mr Burgess said: "I am aware that there is speculation that these deaths were not the result of the sad but relatively straightforward road traffic accident in Paris."
Mr Burgess said Sir John's findings would help him decide whether the inquest, at the Queen Elizabeth II Conference Centre in London, needed to examine the rumours surrounding the crash.
He said police would be asked to interview potential witnesses to determine the extent and relevance of their evidence.
Mr Burgess said it was unusual for an inquest not to be opened soon after a death - even if it was quickly adjourned - but that there had been too little information to hold a hearing soon after Diana and Dodi's deaths.
Adjourning the case for 12 to 15 months he said the delay was necessary to consider the vast amount of information from the French investigation, and issues such as which witnesses to call.
Arriving for Diana's inquest, Harrods owner Mohamed Al Fayed, said: "This is what we have been waiting for, for six years.
"At last, I hope we can see the light."
Mr Al Fayed maintains the deaths of his 42-year-old son and the 36-year-old princess were the result of a conspiracy and is calling for a full public inquiry.
He was also present when his son's inquest was opened at 1500 GMT in Reigate, Surrey, by Mr Burgess - who as well as being coroner of the Queen's Household is coroner for Surrey.
Afterwards, he repeated his belief that Diana and Dodi were the victims of "horrendous murder" masterminded by the establishment.
Diana's personal bodyguard, Trevor Rees Jones, was the sole survivor after their speeding Mercedes crashed in an underpass on the short trip from the Ritz Hotel to Mr Fayed's Paris apartment.
But he has said he can recall little of what happened.
Mr Burrell welcomed the inquest into Diana's death.
"I have always thought that an inquest would be a good idea. I will co-operate with the
inquest in any way that I can."