The cost of inquiries into Princess Diana's death is nearing £7m
There is "not a shred of evidence" that the Duke of Edinburgh ordered Princess Diana's death or that it was organised by MI6, the inquest has heard.
Coroner Lord Justice Scott Baker said jurors could find that Diana and Dodi Al Fayed died accidentally, or because of negligence.
Many conspiracy theories suggested by Dodi's father Mohamed about the deaths were without foundation, he insisted.
The couple died in a car crash in Paris in August 1997.
Speaking to the jury after six months of evidence, the coroner said many of Mohamed Al Fayed's theories about the crash were "so demonstrably without foundation" that even his lawyer was no longer pursuing them.
He put aside theories which, he said, had been encouraged by the media for the past 10 years, as he began to go through evidence from more than 250 witnesses.
Mohamed Al Fayed was in court to hear the coroner
He said of Mr Al Fayed's ideas: "They are not being pursued because there is not a shred of evidence to support them.
"Foremost among them is the proposition that Diana was assassinated by the secret intelligence service (MI6) on the orders of the Duke of Edinburgh.
"There is no evidence that the Duke of Edinburgh ordered Diana's execution, and there is no evidence that the secret intelligence service or any other Government agency organised it."
He said the lengthy and costly inquest had played a crucial role in testing those theories - but that some people would continue to believe in the murder theory no matter what the verdict was.
Of the alleged murder he said: "There are no doubt those who genuinely believe this to be the case and will continue to do so regardless of any verdict you return.
"You have heard the evidence and it is your decision that matters and not anyone else's.
"You will have been reassured to have heard that Mohamed Al Fayed told you on oath that he will accept your verdict; no doubt the other interested persons will do likewise."
He said that he and the jury - plus one Diana fan who sat through all the proceedings with the words "Diana" and "Dodi" painted on his face - were the only ones to hear every word of evidence.
Lord Baker gave the jury five verdict options, and added: "I have determined that it is not open to you to find that this was unlawful killing by the Duke of Edinburgh or anyone else in a staged accident."
The five options included unlawful killing by grossly negligent driving of the paparazzi in the following vehicles; unlawful killing through the gross negligence of the driver Henri Paul; and unlawful killing by the grossly negligent driving of both the following vehicles and Mr Paul.
A verdict of accidental death could be returned if none of the previous verdicts are established. The jury was also given the option of an open verdict.
Lord Baker said it was regrettable that there had been some witnesses "who it appears have told lies in the witness box or elsewhere", naming former butler Paul Burrell as one of those who were "liars by their own admission".
Mr Burrell appeared at the inquest for three days in January, but in a video recording obtained by the Sun newspaper he apparently claimed he introduced "red herrings" during his evidence and held back facts.
He then refused to re-appear at the inquest to explain discrepancies between his evidence and comments reported in the newspaper.
At the time, the coroner said he could not compel him to give evidence because Mr Burrell lives outside the court's jurisdiction in the US.