03/02/2006 at 08:00 AM EST
Ever since her 1997 death, conspiracy theorists have insisted that Princess Diana and her lover Dodi Fayed were murdered. And it hasn't helped Buckingham Palace that the loudest is Fayed's own father: Mohamed Al Fayed, the megarich owner of Harrods.
Now, PEOPLE reports in its latest issue, Al Fayed has ramped up his war against the Windsors by telling a freelance journalist that Di's former father-in-law, Prince Philip, was a "Nazi" and a "gangster" who plotted to kill the pair.
Preposterous as the charges sound, they came on the heels of newspaper reports that Henri Paul, the driver who died with the Princess and Fayed in a 1997 car wreck, was a spy and that Diana was wiretapped by U.S. intelligence.
Not all take Al Fayed's accusations seriously. But Lord John Stevens, former commissioner of Scotland Yard, did tell a TV interviewer in January that the inquiry, due to conclude this summer, was "far more complex ... than any of us thought."
A source close to the inquiry also tells PEOPLE that Paul was a secret agent – or at least an informant. "He was certainly paid by France's intelligence service, but you can probably add British secret service, maybe some others." (Though his job as deputy security chief at the Ritz in Paris paid around $35,000, PEOPLE's source confirms that Paul held bank accounts totaling approximately $200,000.)
Still, many Di watchers say the spy talk doesn't mean she was a victim of foul play. "It's normal for intelligence agencies to have staff at hotels on retainer," says Martyn Gregory, author of Diana: The Last Days.
It will take far more than that for Al Fayed to give up his mission. "I'm prepared to put all my wealth and resources," said the mogul, "into showing that Diana and Dodi were murdered."
For more on the story, pick up the new PEOPLE, on newsstands Friday.