In June 2018, the Moon Jae-in government promoted the adjustment of investigative powers as its national task to reform authorities. The objective of the adjustment of investigative powers is to strengthen the independence of police in investigation while reducing the investigative powers of prosecution, which assures that the relationship between the prosecution and the police is not vertical but equal and cooperative. As the police’s investigative independence has been reinforced, it is necessary to closely examine the nature of the adjustment of investigative powers, changes in practice, and the external and internal assessment, presenting policy suggestions.

The key to the adjustment of investigative powers is by recognizing the police’s power to terminate the primary investigation, to send the case to the prosecution if it is suspected of a crime or to close the case first by a decision not to send. Opinions are divided on whether the police’s power to terminate the investigation is provisional or final. The revised Criminal Procedure Act arranged various control devices for the police’s decision to send or not send. The controls for the decision to send are defined as the prosecution’s power to not indict, request for supplementary investigation, and exclusion of duties or disciplinary action against the police. As the controls for the decision not to send, the request for re-investigation, objection, and request to send are stipulated. In addition, there are also controls for the decision to suspend the investigation.

In this study, to examine the changes after the adjustment of investigative powers, the change in the number of cases handled by the police, the number of requests for supplementary investigation, the request for objection, and the request for corrective action for the suspended investigation were analyzed by using statistical data analyzed by the National Police Agency and statistical data analyzed by the prosecution. Also, the responses to the changes in police practice were reviewed. Given the materials, criticism has been raised as the limitations of police investigation expertise have been found even though the independence of the police has been reinforced. Although the National Investigation Headquarters has recently made its efforts, such as improving the quality of the police, introducing an investigation review system, and implementing qualification management, considering the survey results, it is generally uated that it is still insufficient. In particular, continuous retraining is needed in matters that have been uated as relatively insufficient compared to the prosecution.

Considering the internal uation of the police, the police investigators agreed that the prosecutor’s discretion and direct investigation activities become more limited than in the past. Despite being overloaded with work due to the introduction of the decision not to send, the increase in manpower was not sufficiently carried out, resulting in delayed procedures and a phenomenon that investigators are evading in the investigation department. The commonly proposed measures to overcome these problems were to increase the number of investigators and cultivate investigative expertise.

In this study, suggestions on ways to improve police investigation expertise were discussed. The policies presented by the National Investigation Headquarters, such as the investigation examiner system were reviewed. And whether the current system contributes to the protection of the rights and the good of the common people were also discussed. In conclusion, this study emphasizes that the investigation expertise of the National Investigation Headquarters and the specialization of police investigations should be strengthened while harmonizing citizens’ rights and legal stability.