LONDON, England (CNN) -- The inquest into the death of Princess Diana in a Paris car crash in 1997 returned a verdict of unlawful killing on Monday, blaming "grossly negligent" driving by her chauffeur and pursuing photographers for the car wreck.
Diana, Princess of Wales, died in a Paris car crash on August 31, 1997.
Coroner Lord Justice Scott Baker, holding the inquest into the deaths of Diana and her boyfriend, Dodi Fayed, had earlier Monday told the 11 jurors that he would accept a verdict if nine of them agreed. The jury had been deliberating since last Wednesday, April 2.
The jury's first task was to decide whether French investigators got it right within days of Diana's death when they concluded that her speeding driver, Henri Paul, was drunk.
The second issue for the six women and five men was whether the paparazzi who chased the princess around Paris bore a heavy responsibility for the deaths.
On both counts their answer was yes. Watch report on the jury verdict »
Baker also told the jury last week to consider whether Diana and Fayed would have lived if they were wearing seat belts and whether Diana would have survived had she been taken to the hospital faster.
The jury decided that the fact that the couple were not wearing seatbelts was a contributory factor.
After the verdict had been returned, Lord Stevens, who investigated the crash for the British police during an earlier inquiry, said it had been an unprecedented inquest and that he hoped that those killed would now be allowed to rest.
"There have been a number of allegations which have been unfortunate," said Stevens, referring to the conspiracy theories raised during the inquest by lawyers for Mohammed al Fayed, father of Dodi. "I just hope this can bring closure to what has been a traumatic event for a lot of people."
But a spokeswoman for al Fayed said that he felt vindicated by the jury's verdict and that he was shocked that senior members of the British royal family, French police, pathologists and the paparazzi among others had not been compelled to give evidence.
Al Fayed, who was present for the verdict, said of the couple: "I will always mourn their loss to me and to the world," reported his spokeswoman.
Asked whether al Fayed planned to challenge the verdict by means of a High Court judicial review, Michael Coles, al Fayed's press agent, said: "That is a very difficult route but we are keeping all our options open."
In a statement issued Monday evening, Diana's sons, Prince William and Prince Harry, offered their thanks to jurors "for the thorough way in which they have considered the evidence."
"We agree with their verdicts, and are both hugely grateful to each and every one of them for the forbearance they have shown in accepting such significant disruption to their lives over the past six months," the princes said. They also thanked the rescuers who tried to save the 36-year-old princess and the 250-plus witnesses who appeared during the inquest, "in many cases reawakening their painful and personal memories."
The British inquest into the August 31, 1997, deaths began in October after a decade of British and French police investigations and French court proceedings. The jury's role was to determine how the victims died; it had no authority to blame any individual. See gallery of images related to Diana inquest »
Baker said there was "no evidence" that the British secret service -- or any other government agency -- had anything to do with the crash, as Fayed's father had alleged.
The inquest is the official British inquiry into the deaths of the princess and Fayed while they were fleeing paparazzi photographers. It began October 2 and has cost an estimated £8 million ($16 million), Stevens said.
Diana, 36, and 42-year-old Fayed were killed when the Mercedes-Benz they were traveling in hit a pillar in the Pont de l'Alma tunnel in Paris.
They were being followed at the time by the paparazzi after leaving the Ritz Hotel. Paul, who was also killed, was drunk and driving at high speed. Bodyguard Trevor Rees-Jones was the sole survivor.
More than 240 witnesses have given evidence, including Diana's close friends, Prince Philip's private secretary, a former head of the Secret Intelligence Service and Diana's former butler, Paul Burrell. E-mail to a friend