Estranged wife of SAS soldier behind Princess Diana murder claims tells police she is 'utterly convinced' by his story It has been claimed officers have interviewed wife of Soldier N 'at length' She has reportedly give a compelling account of his story Soldier 'claimed Diana's driver Henri Paul was blinded by light' before crash Claims detailed in letter from his mother- in- law to police By Martin Robinson and Amanda Williams Claims: Scotland Yard has reportedly interviewed the wife of a soldier that said Princess Diana was assassinated by the SAS The estranged wife of a SAS veteran who claims elite soldiers murdered Princess Diana has told Scotland Yard his story is 'utterly convincing', it emerged today. The former sniper - known only as Soldier N - believes the Princess of Wales' death 16 years ago in Paris was carried out by British special forces who then 'covered it up'. This morning it was revealed his former lover has been interviewed by the Metropolitan Police in a secret location and told detectives the military man is 'telling the truth'. Soldier N claimed driver Henri Paul was blinded by an intense flash of light moments before he lost control of their ­Mercedes and killed the Princess and her lover Dodi Fayed. 'She was utterly convinced he was telling the truth when he said the SAS was involved in Diana and Dodi's deaths,' a source told the Daily Express. It came out when there was no ­marital strife and when they were still friends. The Express reports that detectives travelled to a secret location to interview both his estranged wife and his mother-in-law last week. Detective Chief Inspector Philip Easton is said to have questioned the sniper's estranged wife at length. She reportedly had 'total belief' in his story and reportedly gave a 'compelling account' of her husband's claims. She denied the story that an SAS hit squad was involved in the deaths was 'fantastic', and said that the veteran had repeated the claims several times. Diana, Dodi and their driver were killed when the Mercedes crashed in the Pont de L'Alma underpass in Paris in August 1997. Bodyguard Trevor Rees-Jones was critically injured but survived. Crash: Conspiracy theories have long surrounded Diana's death in Paris in 1997 despite the official finding that it was an accident caused by paparazzi photographers Princess Diana and with Dodi Fayed (pictured together on the night they died) were killed alongside Henri Paul when the car crashed in a Paris tunnel An inquest in 2008 found that Princess Diana and Dodi Al Fayed were unlawfully killed due to the "gross negligence" of driver Henri Paul, a security manager at the Paris Ritz Hotel, who had been drinking. But the families of Dodi and Mr Paul have long claimed it was a murder. Soldier N's credibility has been called into question, with Royal bodyguards and Met experts calling it a 'mystifying stunt' based on 'nonsense' evidence. He is currently in jail for illegally keeping guns at home, and was described by those who know him as a 'loose cannon'. As well as hiding weapons in his house, in a 'reign of terror' on his family Soldier N allegedly attacked his son after mistaking him for the Taliban. Soldier N is also accused of saying he could enlist the help of his colleagues to ensure his wife - the mother of his two children and the woman who defended his theory to police - would "disappear." His allegations surfaced in a letter linked to the trial of former sniper Danny Nightingale. Revelation: The new claim emerged in connection with the trial of Danny Nightingale, pictured with his wife The families of Henri Paul and Dodi al Fayed (pictured with Princess Diana) have always believed there was a murder plot The document was written by the mother-in-law of 'Soldier N', Nightingale's housemate, in September 2011 and sent to military prosecutors. The eight-page correspondence claims Soldier N boasted it was the SAS that had "arranged Princess Diana's death" and that it had been "covered up." Sergeant Nightingale, 38, was found guilty last month of illegally possessing a pistol and ammunition at a Hereford house he shared with Soldier N. Soldier N, who is serving a custodial sentence for possessing firearms at the same address, was originally reported to the police by his wife, from whom he is now separated. The letter was sent to Soldier N's commanding officer in September 2011 and passed to the Service Prosecuting Authority before the start of the Nightingale trial. All references to the SAS were removed by the SPA. The paragraph referring to the death of Diana says: "He also told her (his wife) that it was the XXX who arranged Princess Diana's death and that has been covered up." Scotland Yard confirmed officers from its specialist crime and operations command are assessing information handed to it by the Royal Military Police. Pictured: The couple at the Ritz Hotel before they both died The letter says Soldier N told his wife there is a "box which members of his unit use for private jobs." They put in the box the name, address and details of what they want done and then one of them who wants to earn extra money does that job.