Zaid al-Hilli, 54, who was detained in June on suspicion of conspiracy to murder but then released, has been "re-bailed until pending further enquiries", police said.
He had been due to return to a police station to answer bail . There was no immediate explanation from the force as to why the renewal had taken place a day earlier than expected.
His brother Saad, Saad's wife Iqbal and her mother Suhaila al-Allaf were killed in the family's BMW estate car in a car park at a beauty spot near Lake Annecy on .
French cyclist Sylvain Mollier was also gunned down, although investigators believe he was not a target and was just in the wrong place at the wrong time.
The al-Hillis' two young daughters survived the shooting. Zainab, then seven, was badly injured while Zeena, then four, huddled behind her dead mother's skirt for hours until police found her.
A judge ruled last week that the two girls, who have spent 10 months in foster care, will now be cared for by two members of their extended family.