Detectives have ruled out growing speculation soldiers from Britain's elite SAS were involved in the death of Diana, Princess of Wales and partner Dodi Fayed.
"Whilst there is a possibility that the alleged comments in relation to the SAS's involvement in the death may have been made, there is no credible or relevant evidence to support a theory that such claims had any basis in fact," Assistant Commissioner Mark Rowley said in a letter obtained by Britain's Sky News.
"Having reviewed the exercise and its findings, I am satisfied that there is no evidential basis upon which therefore to reopen any criminal homicide investigation or refer the matter back to the coroner."
Police received information in August that alleged Special Air Service members or former members were involved in the leadup to the deaths of Diana, Fayed and driver Henri Paul in August 1997.
A team of seven detectives investigated the allegations and were given access to Special Forces Directorate records, and took eight statements, Sky News said.
A police concluding summary said there were contradictions as to whether individuals did or did not make claims that people associated with the SAS had some involvement in the deaths.
"It is not possible to prove conclusively what was, or was not said," the summary said.
"It is, however, very clear that in the extraordinary publicity and conjecture that followed the deaths and the inquests, there will have been those who, for whatever motivation, will have sought to demonstrate particular inside knowledge, or to claim some form of kudos or recognition."
The inquiry came after a so-called Soldier N alleged his old regiment, the SAS, was ordered to kill the Princess in Paris in 1997.
Soldier N allegedly first told his then-wife at their Hereford home in 2008 - after Prince William had visited the regiment's headquarters - that the SAS had murdered Diana.
He reportedly said she was killed by an SAS hit team who flashed a high-powered light into the face of her driver - a technique developed to assassinate enemies of the state. The Mercedes limousine Diana was travelling in crashed in an underpass in central Paris.
Allegations of the SAS's involvement first emerged in a seven-page letter written in 2011 by Soldier N's mother-in-law.
The contents were disclosed following the court-martial of Sergeant Danny Nightingale, after police found illegally held firearms and ammunition at a house he and Soldier N shared.
Soldier N was sentenced to two years at the Military Corrective Training Centre in Essex. Nightingale also admitted the gun offences but after a second court-martial was sentenced to two years suspended for 12 months.
Soldier N reportedly denied making the claim, and said his former wife was "trying to cause trouble".
Extensive inquiries have concluded the direct cause of Diana's death was Paul speeding while under the influence of alcohol.