A man arrested at Glasgow Airport was not the French fugitive suspected of murdering his wife and four children eight years ago, it is reported.
The sensational twist in the case was announced on Saturday and French sources have blamed British police for the mistake.
A “partial” fingerprint sample had erroneously led to claims that the easyJet passenger was wanted aristocrat Xavier Dupont de Ligonnès.
There was wild speculation that De Ligonnès may have fled France and settled in Scotland with a new wife following the 2011 bloodbath.
But “DNA tests have now proved that the man (arrested in Glasgow) is not the murder suspect”, said a French investigating source.
“There has been a very big mistake in Scotland, where officers are now carrying out an internal enquiry. Claiming publicly that the man was Xavier Dupont de Ligonnès was a very big mistake.”
Police Scotland had said earlier that a man was in custody in connection with a European Arrest Warrant.
The AFP news agency said the 58-year-old was allegedly travelling under a false name when the flight arrived in Glasgow from Paris.
The state prosecutor in Nantes, France, had said fingerprint and DNA tests were under way to determine the passenger’s identity.
De Ligonnès went on the run in 2011 after the bodies of his wife Agnes, 49, and children Tomas, 21, Arthur, 18, Anne, 16, and Benoit, 13, were found buried in the garden of the family house in Nantes, western France, along with their two pet Labradors, Jules and Léon.
A female witness on Saturday told the Ouest France newspaper that De Ligonnès had since managed to start a new life in Scotland.
“A very reliable source specifies that the fugitive had even remarried in Great Britain,” the newspaper reported.
There was no indication as to whether this information had been passed on to the police, it added.
It came after Scottish police had said the “digital fingerprint” of a man who landed in Glasgow on easyJet flight U26884 at 2.30pm on Friday corresponded to that of De Ligonnès.
He was using a passport stolen in 2014 belonging to a man called Guillaume Joao, it was orginally claimed, but then this information was retracted.
Mr Joao’s home in Limay, in the Yvelines department 40 miles of Paris, was raided by police.
“Mr Joao looks nothing like De Ligonnès, and nor was the man who was arrested in Glasgow,” said a French investigating source.
“The digital fingerprint identification was only partial,” he added.
Pierre Sennès, the Nantes prosecutor, had called for “prudence”.
Last year police searched underground caves and abandoned potassium mines in the area around Roquebrune-sur-Argens, in the south of France, where De Ligonnès was spotted by a CCTV camera in April 2011.
There was no sign of him there either.
Police Scotland said earlier: “On Friday, 11 October 2019, a man was arrested at Glasgow Airport and remains in police custody in connection with a European Arrest Warrant issued by the French Authorities.
“Inquiries are ongoing to confirm his identity and we continue to liaise with our colleagues in the relevant agencies.”