Updated

Swiss police now say the missing 6-year-old twins might never have left Switzerland at all — throwing the entire investigation into doubt — and French investigators say they could even be alive.

After spending weeks searching for the girls, Swiss police and the public prosecutor's office for the canton (state) of Vaud said Wednesday there is no way of telling whether any witnesses actually saw Matthias Kaspar Schepp whisk away his daughters from Lausanne to Marseille, France, and then to the French island of Corsica and possibly to Italy.

"Anything is possible now," Vaud police spokesman Jean-Christophe Sauterel told The Associated Press on Wednesday night. "We can't rule anything out."

The surprise turn of events came as authorities held news conferences in Marseille and later in Lausanne. Investigators say they have been unable to confirm any of the alleged witness sightings of the girls since they were seen playing at 1 p.m. Jan. 30 with a neighbor's child in their hometown of Saint-Sulpice, part of Lausanne, along Lake Geneva.

Until Wednesday, the search had focused on Corsica, where Schepp was thought to have brought the girls. He later committed suicide in Italy on Feb. 3, police said.

Swiss police said investigators were now looking for a large, dark station wagon with Swiss license plates that was similar to the one driven by Schepp. Sauterel told the AP that witnesses had reported seeing the Audi A6 in different places in Corsica at exactly the same time.

The sighting of the second Audi is "confusing the witness accounts," Sauterel said. He added that it should, however, be easier to find the driver of the second car to eliminate its route from investigations as it was during a low tourist season.

Sauterel and Eric Cottier, the public prosecutor for Vaud, told reporters the implications of that include the possibility the girls never left Lausanne.

Cottier said 100 people have called or written to the police with information, but none of it has led to evidence of the girls' whereabouts.

"In Switzerland, every tip, every concrete thing, was checked to find the two girls," he said.

They said Italian police had found fragments of the GPS navigation system from Schepp's Audi on the railroad tracks not far from where he threw himself in front of the train in Cerignola, Italy.

The GPS was too damaged to retrieve any data from it, and Sauterel said it seemed Schepp had removed the GPS and tried to deliberately destroy it. He also said the will police found that Schepp had written on Jan. 27 — the same day his wife e-mailed him to say she wanted a divorce — did not contain any details of an alleged plan to kill the children, contrary to some news reports. Schepp and his wife had been separated for six months.

Hope of finding the twins alive has faded since last week, when a letter from their father surfaced, saying he had killed them but leaving no other clues. Schepp committed suicide the same day he mailed the letter to his wife from Italy.

Investigators in France, Italy and Switzerland have been trying to trace the father's path after he left his home near Lake Geneva on Jan. 30. He then traveled to southern France, Corsica and Italy — either with or without his daughters.

Investigators from the three countries huddled in the southern French city of Marseille on Wednesday to coordinate efforts. They said no possibilities had been ruled out, including that the girls are still alive.

"The inquiry is still very active," Marseille Prosecutor Jacques Dallest told reporters.

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Don McCaughan in Marseille, France contributed to this report.