Updated

The nearly month-old search for missing Swiss twins is again focusing on the French island of Corsica, where their father visited days before throwing himself under a train in Italy, Swiss police said Friday.

Since their disappearance Jan. 30, the search for 6-year-old twins Alessia and Livia Schepp had focused on Corsica. Witnesses had claimed to have seen the girls board an overnight ferry Jan. 31 that was headed to Corsica from Marseille, France, with their father, Matthias Kaspar Schepp.

The police say a witness saw Schepp throw himself under a train in Italy on Feb. 3, the day his body was found. He had written a letter to his wife that day saying the girls were resting in peace and he would kill himself.

Last week the Swiss and French police said those witness accounts were no longer certain and the girls could be anywhere from Switzerland to France to Italy.

Now, Swiss police in the canton (state) of Vaud say they are "giving the most weight to the Corsica trail, but without rejecting other hypotheses" — despite the lack of any formal proof the twins were on the overnight ferry.

The police said Friday the girls were last seen with their father at a beach near Morges, Switzerland mid-afternoon on Jan. 30 — and they are examining more closely his movements between Switzerland and Marseille.

The girls had been spending the weekend with their father, who was supposed to bring the girls to school the next morning.

Investigations by police in Vaud and Fribourg cantons established no link between the girls' disappearance and that of a Swiss woman named Katia Iritano, who went missing on Jan. 25. Some had speculated she might have known the girls' father.

The police said objects examined from Schepp's home "have not shown the presence of sleeping pills or toxic products that might offer evidence that the little girls were killed in the house."

But the probe is also looking into why the father did not carry suitcases or other bags.

On Wednesday, about 200 friends and neighbors of the girls' mother Irina Lucidi marched through her Swiss town to express support and encourage the police to continue searching in hopes that girls are alive.