Prince Charles was spoken to by police in an investigation over allegations he planned to kill Diana, said a former head of Scotland Yard.
Lord Stevens reportedly said that the police launched a probe after a note written by Diana was found where she predicted she would die in a car crash.
The police chief told the Daily Mail he had to question Charles over Diana’s claim that she would be killed through “brake failure and serious head injury” so Charles could marry Tiggy Legge-Bourke, William and Harry’s former nanny.
Diana also said that Camilla was just a “decoy so we are being used by the man in every sense of the word,” that was left at Kensington Palace for her butler Paul Burrell.
Charles was spoken to as a witness, not a suspect, on December 6, 2005, as part of a three year investigation. The Prince of Wales said he did not know why Diana had written the letter, it is reported.
Lord Stevens also told the Daily Mail that police would have spoken to ex-BBC journalist Martin Bashir over the suggestion he may have made her more paranoid by exploiting her insecurity.
Bashir was found to have used fake bank details to con Diana into giving a Panorama interview in November, 1995.
“If there’d been an allegation then that Bashir had produced allegedly fake documents to Princess Diana, which is a criminal offence, we’d have investigated it,” Lord Stevens told the Daily Mail.
“My goodness me, we would have done. But this has only come out recently which is unfortunate.”
He added: ”We don’t know what Bashir was saying to Diana but if he had put the fears in her mind which had caused her to write that note then that is what caused us to interview Charles. When we watched the Panorama interview at the start of the inquiry it didn’t cross our mind that Bashir could have done anything fraudulent.”
Diana died with her boyfriend Dodi Al Fayed and their driver Henri Paul when their Mercedes crashed in a Paris tunnel.
In April, 2008, a narrative verdict of “unlawful killing [due to the] grossly negligent driving of the following vehicles and of the Mercedes” was returned by an inquest that specified Paul’s drink driving and the failure to use seatbelts.