White paper on crime 2018 Part2/Chapter2
The judicial police officials are to refer every criminal case to public prosecutors, except cases subject to disposition as trivial offenses (certain minor offenses with especially mitigating factors which satisfy the public prosecutor’s predesignated criteria are not required to be referred to public prosecutors pursuant to the proviso of Article 246 of the Code of Criminal Procedure) and certain violations of Road Traffic Acts subject to Hansokukin (administrative fine).
Public prosecutors investigate cases referred by the police or other special judicial police officials (officials of investigative agencies other than police with a specific jurisdiction; e.g. coast guard officers, narcotics agents, etc.). In addition, where necessary, public prosecutors may institute investigation as their own initiative or as a response to a complaint or accusation directed to the office. In concluding the investigation, they decide whether or not to prosecute the suspect, based on factors such as whether or not his/her act constitutes an offense and if the act needs to be punished.