Thank you for the map, Hazel!
I'm not sure if he was seen on the ferry to Italy, but he had to get there somehow from Corsica, so hopefully someone somewhere saw something, or even better, there were cameras.
Police think that he may never have taken the girls abroad at all, because they found their IDs at home (borders are mostly open here, but I wouldn't risk traveling without ID), and their car seats (at 6 years, they still have to use them, legally) were in the mother's car.
bazonline.ch (Article in German)
PS: Should I not post links if they aren't in English? Most coverage here will be in German or French. I'm rather new to posting here, so I want to make sure I'm not doing something incredibly stupid or against the rules.