French prosecutors confirmed on Monday that one of the Islamic State jihadists seen unmasked in a video claiming the execution of a US aid worker and Syrian soldiers was a French citizen.
"Circumstantial evidence confirms the involvement of a Frenchman in the decapitation of Syrian prisoners shown in an Islamic State video released on Sunday," the Paris prosecutor's office said.
Interior Minister Bernard Cazeneuve had earlier said the man was believed to be Maxime Hauchard, born in 1992 in Normandy in northern France who "left for Syria in August 2013 after a stay in Mauritania in 2012."
The man is seen in a gruesome video released on Sunday that shows the head of American Peter Kassig and the beheadings of at least 18 men described as Syrian military personnel.
Cazeneuve said there was a "strong possibility that a French citizen was directly involved in these despicable crimes."
An intelligence source said it was being verified whether a second French citizen was among the jihadists seen in the video.