The latest wrinkle, says CBS News Correspondent Sheila MacVicar, involves reports Diana's driver on the night she died was a French spy.
MacVicar says the most complicated conspiracy theory argues Diana and boyfriend Dodi Fayed were murdered by British intelligence agents, and driver Henri Paul's' blood was tampered with.
Now, there are allegations the United States was tapping the princess's phone calls and that there is evidence in those transcripts that she was assassinated.
Almost all the conspiracy theories revolve around Paul, MacVicar points out.
The official French inquiry found that he was drunk.
Paul was a security official at the Ritz Hotel, and employee of Fayed's father, Mohamed Al-Fayed.
"He actually believes that she was murdered," says royals watcher Robert Jobson. "The reality is, of course, also, that his car, his driver, were involved in this crash; therefore there will be people that believe that he is ultimately responsible not only for the death of his own son, but for the death of the princess."
The British inquest into Diana's death has launched a new investigation, whose aim is to put an end to the questions, MacVicar observes.
The head of the British inquiry, Lord Stevens, has remarked, "It's right to say that some of the issues raised by Mr. Fayed have been right to be raised. We're pursuing those. It's a far more complex investigation than any of us thought."
And, says MacVicar, far more confusing for the newspaper-reading public in Britain.
Over the weekend, the Sunday Times said Paul worked for a French intelligence agency, suggesting there might be something to the conspiracies.
But, MacVicar notes, French officials have long acknowledged that Paul was an informant for the domestic security agency.
As for blood samples being tampered with, a senior French prober tells CBS News they are confident they took measures to ensure the samples could not be tampered with or switched, and that the British inquiry, like the one in France, will find that Diana died at the hands of a drunk driver.
This month, three French photographers were . They were symbolically fined the equivalent of about $1.20 each.