The Public Prosecutor's Office is composed of all the judges working in the judicial courts and tribunals, in charge of representing the interests of society and of ensuring that public order is respected and the law is enforced. The Public Prosecutor's Office is hierarchical (Chief Public Prosecutor, Public Prosecutor, Deputy Public Prosecutor, Assistant Public Prosecutor) and subordinate to the Minister for Justice. It does not benefit from the same absolute security of office as the judges (judges that cannot be moved, suspended or removed without their opinion, except for disciplinary or health reasons).
The Public Prosecutor's Office decides on the timeliness of prosecution. If it decides to prosecute, it refers the case to a court or to the examining magistrate, depending on the seriousness and complexity of the case, or to the juvenile affairs judge for cases against minors. It may order an alternative to prosecution (remedy of the damage, compensation to the victim, therapy order for drug addicts, etc.). Last, it may decide to close the case if the perpetrator is unknown or if prosecution seems to be untimely, particularly when the prejudice is small-scale.
Source : ministère de la Justice (site : http://justice.gouv.fr)