The investigating judge is a judge who directs legal investigations in complex criminal affairs. To do this, the case must be referred by the State prosecutor or the victim, on certain conditions.
Using rogatory letters, he/she can request the assistance of the criminal investigation police department.
The investigating judge decides to indict a suspect, or requests that they be remanded in custody or placed under judicial supervision.
During his/her investigation, which must be impartial, a dossier is constituted that will be submitted to the competent jurisdiction. If the charges are sufficient, an ordonnance de renvoi (committal for trial) may be issued, alternatively an ordonnance de non-lieu (non suit), dismissing the case for lack of evidence.