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LONDON, England (CNN) -- More than nine years after Princess Diana's death, British authorities have finally released the long-awaited official findings from an investigation into the 1997 Paris car crash that killed her.
The exhaustive three-year report, out Thursday, and a public inquest next year are an attempt by authorities to end conspiracy theories surrounding the late princess's death.
The Scotland Yard inquiry found claims that the princess was murdered were unfounded, that Diana was not pregnant at the time of the crash, nor was she engaged or about to get engaged to Dodi Fayed. (Full story)
Diana, 36, her friend Fayed, 42, died in the August 31, 1997, crash in a Paris tunnel.
They were killed along with chauffeur Henri Paul. Paul was drunk and driving at twice the speed limit before the crash, Thursday's report found.
Journalist and royal watcher Robert Jobson told CNN's American Morning program Wednesday, ahead of the report's release, that he expected Thursday's findings to echo a two-year French inquiry that blamed the crash on Paul, saying he was drunk, under the influence of anti-depressants and driving too fast.
"I don't think we'll have any bombshells. They're certainly not going to say this is a murder conspiracy. In fact, I'm sure they'll say, 'This is an accident,'" Jobson said.
The British inquest was opened in January 2004 and then royal coroner Michael Burgess asked police to hold a top-level investigation into the circumstances surrounding the deaths.
He said he wanted John Stevens, the former head of London's Metropolitan Police, to examine conspiracy theories that the couple were murdered by British spies to cover royal embarrassment about their relationship.
The verdict that the world's most celebrated princess died a common death at the hands of a drunk driver will be a finding hard to swallow for some who have speculated that the British government -- or even members of the royal family itself -- had plotted to kill her.
Stevens' investigation failed to interview 18 witnesses who were spoken to by the French investigative team.
Jobson said: "It may just be -- and it's possible -- that they are not reliable witnesses," Jobson said.
"It may just be that the police are happy to rely on those statements. However, after an 8 million pound ($15.7 million) investigation that's been funded by the British taxpayer, I would have thought it would be appropriate to start at the very beginning and re-interview eye witnesses and everybody who's been interviewed by the French inquiry to ensure nothing has been missed."
More troubling for some, the inquiry into Diana's death confirms CNN reports that Henri Paul, the chauffeur who drove the Princess to her death, was a paid informant for the French intelligence service.
According to Nicholas Davies, the author of "Diana: Secrets and Lies," Diana was killed by British intelligence because of her political power and her media prowess.
Princess Diana's public campaign against land mines had already forced some armies to give them up.
Davies' theory is that British spies, aided by their French counterparts, bumped off the Princess, pointing the finger at her driver and rigging her seat belt so she couldn't use it.
But no one has done more to fuel the mystery of her death than Diana herself.
Her long-time butler, Paul Burrell, claims to have a note written by Diana in which she said she lived in fear that her husband Prince Charles was trying to kill her, adding fuel to the flames.
Allegedly she wrote: "My husband is planning an accident in my car, brake failures and head injury to make the path clear for him to marry."
And yet the only person to survive the crash, Diana's bodyguard Trevor Rees-Jones, has maintained there is no truth to any of the conspiracies.
There are few who believe any member of the royal family had anything to do with Diana's death, but the car crash, the chauffeur and Diana's fear that she would be killed have added to the mystery of her death.
After Thursday's report and next year's inquest, for which Prince Charles has already been interviewed, the case will be officially closed.
Few observers believe anything will put an end to the public interest and morbid fascination with Diana -- the most recent originating from media reports in Britain this week saying the U.S. Government was spying on Diana in the last hours of her life. It's a claim the national security agency denies.
Author of "The Real Diana," Lady Colin Campbell, told CNN: "I think many people find it really difficult to believe that a beautiful, 36-year-old princess with everything to live for could just die in a tragic accident.
"I have no doubt that 100 years from now people will still be saying that Diana's death was a great mystery."
CNN's Paula Newton contributed to this report.
Conspiracy theories still surround the death of Princess Diana.
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