Roman Polanski promised and crossed his heart and hoped to die that he would not leave Switzerland if he were let out of jail. He would wait patiently to see whether he would be extradited to the U.S. where he would be put in prison in uncomfortable circumstances. He would under no circumstances consider crossing the border into France which does not extradite its citizens. Polanski is a French citizen.
A Swiss court, remembering that another court had heard a similar promise, said, no deal.
Or as Le Monde puts it more elegantly:
Le tribunal pénal fédéral de Bellinzone a rejeté, mardi 20 octobre, la demande de mise en liberté provisoire du cinéaste franco-polonais Roman Polanski, détenu en Suisse depuis plus de trois semaines sur mandat américain, en raison des risques “élevés” de fuite.