A man arrested at Glasgow Airport on suspicion of murdering his family eight years ago was detained by mistake.
Identity checks have shown that the man is not Xavier Dupont de Ligonnes, Police Scotland confirmed.
The 58-year-old has been on the run since his wife and four children were found buried at their home in Nante in 2011.
The detained man was stopped at the airport after arriving on a flight from Paris.
In a statement Police Scotland said: "On Friday, 11 October 2019, a man was arrested at Glasgow Airport following information provided to police.
"He was held in police custody in connection with a European Arrest Warrant issued by the French Authorities.
"Inquiries were undertaken to confirm the man's identity.
"Following the results of these tests it has been confirmed that the man arrested is not the man suspected of crimes in France.
"The man has since been released."
Mr Dupont de Ligonnes is suspected of murdering his wife Agnès, 48, and his children, Arthur, 21, Thomas, 18, Anne, 16, and Benoît, 13, whose bodies, as well as those of the family's two dogs, were discovered buried in the garden of the family house in Nantes in 2011.
The murders, known as the "Nantes slaughter", deeply shocked France at the time.
French prosecutors previously said he killed his victims in a "methodical execution", firing two bullets from a silenced weapon at close range into their heads, before he rolled them in lime and buried them under cement.
Mr Dupont de Ligonnes reportedly told his teenage children's private Catholic high school that he had been transferred to a job in Australia.
And he also allegedly told friends he was a US secret agent who was being taken into a witness protection programme.
A large police operation was mounted in the Var region of southern France in January last year after witnesses reported seeing a man resembling him near a monastery.