Maelys de Araujo vanished in the early hours of Sunday, August 27, in the southeastern village of Pont-de-Beauvoisin, where she was attending a wedding with her parents.
A 34-year-old local man, who was among the guests, was remanded in custody on September 3 on charges of "kidnapping, illegal confinement or arbitrary detention" after the girl's DNA was found in his car.
But despite an extensive search effort, no sign of her has been found. The suspect has denied any wrongdoing, saying Maelys briefly got into his car with another child and later returned to the wedding party.
Maelys de Araujo. AFP.
Searches of the nearby Chailles gorges in Savoy were ended on Tuesday, the source told AFP, while a search of a nearby lake will continue Wednesday.
"We're exhausting the possible areas where we could have results," the source said, saying searches would now be carried out based on any progress in the investigation.
The disappearance of Maelys caused shock in the tranquil Isere region of mountains, woods and lakes.
Sniffer dogs lost her scent in the car park outside the wedding venue, raising fears she was kidnapped and whisked away by car.
Scores of police search and rescue teams, divers and cavers have combed the area for signs of her, while officers questioned all the wedding guests.