The position of Budget Minister Jérôme Cahuzac in President Hollande's government looks increasingly under pressure after a preliminary formal investigation has revealed that a key element in the allegations surrounding his undisclosed Swiss bank account has been authenticated. Technicians and witnesses have confirmed that a tape recording in which Cahuzac is heard discussing his bank account at UBS in Geneva is genuine, and that the voice indeed belongs to the socialist politician. Cahuzac has always denied having the account. Investigators now believe the affair should be handed over to an independent examining magistrate. Fabrice Arfi reports.