Former Metropolitan Police Commissioner Lord Stevens is giving evidence at the Diana, Princess of Wales inquest.
Britain's former top policeman produced the Paget report into the Paris crash which killed Diana, her lover Dodi Fayed and driver Henri Paul in August 1997.
It is reported that the investigation cost £3.6 million.
Lord Stevens launched Operation Paget in 2004 at the request of Michael Burgess, the Royal Coroner who was overseeing the future Diana inquest at the time.
His brief was specifically to investigate allegations that Diana and Dodi were murdered, the theory most commonly associated with Dodi's father, Mohamed al Fayed.
The former Scotland Yard chief rejected the murder claims when the Paget report was published in December 2006.
The inquest jury, sitting in central London, will return a separate verdict later this year on the evidence they have heard.
