Article 657 of the French Code of Criminal Procedure
When two investigating judges, belonging to the same court or to different courts, are simultaneously seised of the same offence, the public prosecutor may, in the interests of the proper administration of justice, request one of the judges to relinquish jurisdiction in favour of the other. The court may only relinquish jurisdiction if both judges agree. If the conflict of jurisdiction persists, the procedure shall be carried out, depending on…