It was found that cases the prosecution sent back to police with requests for supplemental investigation topped 110,000 last year, the most on record. As the authority to request supplemental investigation, introduced after the 2021 adjustment of investigative powers, has degenerated into a "case ping-pong" tool between prosecutors and police, critics say the burden of delayed investigations and repeated procedures is being shifted to citizens.
According to materials submitted by Democratic Party of Korea lawmaker Yang Bu-nam from the Korean National Police Agency on the 2nd, of the 752,560 cases police sent to prosecutors last year, prosecutors requested supplemental investigation in 110,623 cases. That is 14.7% of the total, or about 1 in 7 cases.
Although the total number of cases sent was down from 778,294 in 2024 to 752,560 last year, the number of requests for supplemental investigation instead increased. Requests for supplemental investigation were 87,173 in 2021, 103,185 in 2022, 99,888 in 2023, and 104,674 in 2024, before surpassing 110,000 for the first time last year. The request rate for supplemental investigation, which had hovered between 11% and 13% each year, also entered the 14% range for the first time.
Inside and outside the legal community, some interpret this as numbers revealing the ongoing conflict between prosecutors and police since the 2021 adjustment of investigative powers. Over the authority to request supplemental investigation—introduced in part to make up for the abolition of prosecutors' authority to direct investigations—prosecutors and police still hold diametrically opposed views.
The prosecution's position is that the completeness of maintaining indictments must be strengthened by legal review and evidentiary reinforcement that may be lacking at the police investigation stage. Some in the legal community also say that because a flawless investigation is realistically difficult, the authority to request supplemental investigation is necessary as a check on police investigations.
By contrast, within the police there is considerable discontent that, with the burden of primary investigations growing, administrative resources are being wasted by repeatedly reviewing the same case. Suspicion also persists that prosecutors are attempting to exercise, in a roundabout way, their de facto abolished authority to direct investigations, going beyond a mere check.
The problem is that, as prosecutors and police pass cases back and forth, the burden falls squarely on those involved in the cases. Criminal procedures are prolonged as cases bounce between agencies for supplemental investigation, and not a few parties have been tied up in investigations for years.
The higher the political profile of a case, the more the cycle of transfer, supplemental investigation, and demands for reinvestigation intertwines, repeatedly creating the appearance that prosecutors and police are shifting responsibility to each other.
Representative examples include the case of independent lawmaker Lee Chun-seok's alleged stock trading under borrowed names, in which police pushed back against the prosecution's exercise of the supplemental investigation authority, and the "clothing expense allegations" involving Kim Jung-sook, spouse of former President Moon Jae-in, which police disposed of as no charges despite the prosecution's demand for reinvestigation.