Investigation
The prosecutor shall conduct investigation, whenever a criminal case arises. According to Article 228, the Code of Criminal Procedure, if a prosecutor, based on complaint, information , or voluntary surrender, or for any other reason , suspects the crime having been committed, he/she shall immediately commence an investigation of the crime and the relevant evidence.
　

After completion of the investigation, unless initiating a public prosecution according to laws, the prosecutor shall make any one of the following dispositions:

1.     Non-prosecution

        A Prosecutor shall make a disposition of non-prosecution in one of the following circumstances:

1. The same case is subject to a final judgement previously rendered;

2. The statutory period of limitations has already expired;

3. There has already been an amnesty;

4. A law enacted after the commission of the crime abolishes the punishment;

5. The case involved is one which may be initiated only upon complaint or request, and such complaint or request has been withdrawn or the period within which a complaint may be filed has expired;

6. The suspect is dead;

7. The court has no jurisdiction over the suspect;

8. The act is not punicshable;

9. The crime is exempt from punishment by law;

10. The suspicion of a crime is insufficient.

In addition, if the prosecutor considers it appropriate not to prosecute a case involving one of the offences specified in Article 61 of the Criminal Code, or not to prosecute a juvenile case involving one of the offences for which the maximum principal punishment may be  

imposed does not exceed imprisonment for five years, he/she can make a disposition of non-prosecution after having taken into consideration the provisions of Article 57 of the Criminal Code.

2.     Transfer of jurisdiction

        If a prosecutor considers that a case is not within his/she jurisdiction, he/she shall immediately notify or refer the case to the competernt

        prosecutors’ office 9or military prosecutor) or the competent juvenile court.

Prosecution

If evidence obtained by a prosecutor as a result of investigation is sufficient to show that the suspect has committed the crime, the prosecutor shall instigate public prosecution and prepare the filing of an indictment with the court.

Enforcing prosecution

After instigating public prosecution on behalf of the State, acting as the accuser, the prosecutor takes action against the accused in the court responsible for trial. For example, he/she shall appear in court on the day of the hearing, state the essential points of the prosecution after the court on the day of the hearing, state the esential points of the prosecution after the court in quires the accused, express opinions after the court investigates evidence and make an appeal immediately if the judgement by the court is considered improper.

Assissting in private prosecution

According to the Code of Criminal Procedure, a person who is injured by the commission of crime may intiate a private prosecution if he/she has legal capacity.

But if he/she is a person without or with limited legal capacity or dead, his/her statutory agent, lineal ascendant, or spouse may initiate priviate prosecution. If proper asisstance is not rendered to those people ignorant of laws or legal proceedings, who are initiation private complainants are as a result not substantially protected. Thus, regarding those cases of private prosecution notified with the date of hearing by the court, the prosecutor shall render his/her assisstance by expressing opinions if he/she has factual or legal opinions or thinks the case is seriously concerned with the legal interest of the State or society.

Taking charge of private prosecution

If a complainant, after initiating his/her private prosecution, is found hesitating or unable to proceed or withdraws his/her private prosecution because of corecion or inducement by the accused, and the consequence is serious, the prosecutor shall take charge of the private prosecution, if necessary, except cases which may be initiated only upon complaint. In accordance with the laws, the prosecution in one of the following circumstances:

1. If a complainant, who is summoned in accordance with the law, fails to appear in court without good reason.

2. If he/she appears but makes no statement.

3. If he/she appears but leaves without the permission of the court.

4. If he/she, who initiates a private prosecution dies or loses his/her legal capacity before the conclusion of the argument, is found without a person who may resume the prosecution or whith a person who fails to resume within the statutory time limit, the court shall notify a prosecutor to take charge of prosecuting the case.

5. Conducting the execution of court decisions. In order to enforce the states poser of penalty, prompt the proceeding and maintain the fairness of court decisions, the prosecutor shall be assigned to supervise the execution of court decisions.

6. Performing those functions prescribed by other laws. The prosecutor is authorized to request the court to dissolve a juristic person whose purpose or behavior is found contrary to public order or good morals. According to the Lawyers’ Law, the chief prosecutor of the district court is empowered to directly supervise the local bar association. In addition , any attorney-at-law who has violated the lawyers’ Law should be referred by the chief prosecutor to the Attorney Disciplinary Committee for disciplinary action.