A police spokesman told The Associated Press that police in Glasgow detained a man on Friday who appears to be Xavier Dupont de Ligonnes.
One of the most wanted men in France, Xavier Dupont de Ligonnès, who is suspected of killing his wife and their four children in Nantes in 2011, has been arrested in Glasgow.
Le Parisien said the fugitive was traveling under a fake name, and had been detected due to his fingerprints following a tip-off.
Business manager Dupont wrote in a weird letter to family members at the time that he was a secret agent and he was moving with his family to America as part of a witness protection programme with the Secret Service.
The 58-year-old is suspected of shooting his family dead - Agnes Dupont de Ligonnes, 49, along with Arthur, 21; Thomas, 18; Anne, 16; and Benoit, 13.
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.
He is believed to have covered them in quicklime and wrapped them in sheets before burying them under concrete. Scottish police did not give details of his identity, but Reuters said a French police source confirmed that Dupont de Ligonnes had been arrested.
According to AFP news agency, police had been tipped off that de Ligonnes was heading to Scotland before he boarded his flight to Glasgow at Charles de Gaulle Airport in Paris.
French newspaper Liberation reported that Mr Dupont de Ligonnes had undergone plastic surgery to change his appearance, citing police sources.
A large police operation was mounted in the Var region of southern France in January a year ago after witnesses reported seeing a man resembling him near a monastery.