Article 706-150 of the French Code of Criminal Procedure
During the investigation in flagrante delicto or the preliminary investigation, the liberty and custody judge, at the request of the public prosecutor, may order, by reasoned decision, the seizure, at the advanced expense of the Treasury, of the real estate whose confiscation is provided for by the article 131-21 of the Penal Code. The investigating judge may, in the course of the investigation, order this seizure under the same conditions….