Princess Diana Death Probe: British Media Reports Allegation That Royal's Death Was No Accident

Aug. 18, 2013— -- Conspiracy theories are back surrounding the deaths of Princess Diana and her companion Dodi al Fayed, after British media reported allegations that the couple may have been murdered by British special forces.

Despite a $7 million joint French and British police investigation that concluded that Diana, al Fayed and their driver Henri Paul's deaths in 1997 were accidents, a report in The Mirror claims they were allegedly murdered and it was all covered up.

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The allegation surfaced at a second court martial of Sgt. Danny Nightingale, who was found guilty of illegal gun possession, The Mirror reported. Among the evidence presented at the trial was a letter from a former soldier's estranged in-laws that makes the claim that the SAS (Special Air Service) "was behind Princess Diana's death," the newspaper reported.

On Saturday, Scotland Yard said that British police were looking into new information that has surfaced in connection with the deaths of Diana and al Fayed, but police declined to say what that new information was.

"The Metropolitan Police Service is scoping information that has recently been received in relation to the deaths and assessing its relevance and credibility," Scotland Yard officials said in a statement. "The assessment will be carried out by officers from the specialist crime and operations command.

"This is not a re-investigation and does not come under Operation Paget," the statement said.

Operation Paget looked into conspiracy theories surrounding Diana's and Al Fayed's death in 1997.

A spokeswoman for Mohammad al Fayed, Dodi al Fayed's father, spokeswoman has provided a statement to ABC News regarding the new allegation that his son was murdered.

"Mr. al Fayed has no comment but notes the Metropolitan Police statement that it is investigating," she said. "He trusts that their investigation will be thorough and awaits the outcome with interest."

Mohammad al Fayed has long claimed that Diana and his son were murdered and victims of a cover-up, but he has lost every case he waged trying to prove that.

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The car carrying the couple was traveling more than 85 miles per hour when it hit a concrete pillar head-on in the Place D'Alma underpass, in Paris, on Aug. 31, 1997.

Both were killed, along with the driver, Henri Paul who was later proven to have been under the influence of alcohol at the time.

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The main probe into Diana's death was conducted in 2007-08, and ended up with a verdict of "unlawful killing" and "grossly negligent driving" by Paul and also cited the pursuit of the limo the couple was riding in by photographers contributed to the princess of Wales and Al Fayed's deaths.

As conspiracy theories continues to emerge, Diana's former private secretary Patrick Jephson said any new information must be investigated.

"Imagine if somebody came up and said, I have evidence, new evidence, about the Kennedy assassination, would we just say, oh, forget about it. It's obviously not true. No, we'd investigate it," said Jephson.

Buckingham Palace has declined to comment and Scotland Yard was not releasing any more information at the moment.

ABC News' Susan Donaldson James contributed to this report.