Yoon case spotlights CIO and Korea's tangled web of investigative power

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Yoon case spotlights CIO and Korea's tangled web of investigative power

Published: 19 Mar. 2025, 16:54 Updated: 19 Mar. 2025, 19:05

CHO JUNG-WOO
[email protected]

Audio report: written by reporters, read by AI

President Yoon Suk Yeol walks into the Corruption Investigation Office for High-ranking Officials headquarters in Gwacheon, Gyeonggi, on Jan. 15, for questioning regarding his declaration of martial law on Dec. 3, 2024. [NEWS1]

On Jan. 15, impeached President Yoon Suk Yeol was taken into custody at his official residence in central Seoul after investigators from the Corruption Investigation Office for High-ranking Officials (CIO) executed a detention warrant against him. This marked the first time in Korean history that a sitting president had been placed under detainment.

The second attempt to detain Yoon came nearly two weeks after CIO prosecutors first tried to apprehend him, which resulted in a five-and-a-half-hour standoff with presidential security guards. The security team and Yoon’s attorneys argued that the CIO — a state anticorruption watchdog established to investigate high-ranking officials — lacked the authority to handle insurrection charges and that the presidential residence could not be searched as it is a “high-security area."

The case against Yoon was initially handled by the police and prosecution before being transferred to the CIO on Dec. 16 and Dec. 18, respectively, two weeks after his botched martial law declaration on Dec. 3.

A jurisdictional battle between the three investigative agencies over who had the authority to investigate Yoon’s insurrection charges reignited debate over structural flaws in Korea’s law enforcement system. In 2019, liberal lawmakers fast-tracked bills to establish the CIO and reshape investigative powers. However, this has led to greater confusion and made investigations more convoluted.

Although the police and the prosecution agreed to transfer the investigation to the CIO in late December, Yoon repeatedly defied summonses, arguing that the CIO had no legal basis to investigate him.

President Yoon Suk Yeol is seen riding in a car moving to Seoul Detention Center after being questioned by the Corruption Investigation Office for High-ranking Officials (CIO) at the CIO headquarters in Gwacheon, Gyeonggi, on Jan. 15. [JOINT PRESS CORPS]

Korean law does not explicitly state whether the CIO has the power to handle insurrection cases. A court ruling that refused to extend Yoon’s detention cited “ambiguities” in the CIO Act, hampering the prosecution’s efforts and ultimately forcing them to indict him without direct questioning.

Yoon’s indictment came 54 days after his martial law declaration, partly delayed by jurisdictional disputes among investigative agencies.

The case has become mired in legal uncertainties and institutional power struggles, raising fundamental questions about the effectiveness of Korea’s law enforcement structure.

Police and the Corruption Investigation Office for High-ranking Officials try to go through a bus barricade at the presidential compound in Yongsan District, central Seoul, on Jan. 15. [YONHAP]

CIO launch

The CIO was established in January 2021 as part of former President Moon Jae-in’s push to reform the prosecution and curb its extensive investigative and prosecutorial authority.

The bills for the CIO Act and the redistribution of investigative powers between the police and the prosecution were fast-tracked in April 2019, backed by liberal lawmakers. The primary goal was to reduce the prosecution’s power while also introducing oversight of the police.

During this period, the National Assembly was deeply divided, with rival parties clashing in heated debates and even physical altercations over the reforms.

Lawmakers and aides from the Liberty Korea Party, precursor of the conservative People Power Party, are engaged in a physical altercation with parliamentary officials at the National Assembly in Yeouido, western Seoul, on April 25, 2019, over the fast-tracked Corruption Investigation Office for High-ranking Officials Act. [YONHAP]

The CIO was created as a third investigative authority tasked with probing high-ranking officials, including the president, ministers and lawmakers. However, it was restricted from indicting them. Prosecutors within the CIO were only granted the power to indict justices, prosecutors and senior police officials — a limitation imposed largely due to strong opposition from the prosecution.

The establishment of the CIO was the centerpiece of the liberal Democratic Party (DP)’s long-standing effort to rein in prosecutors and curb politically motivated investigations. However, opposition parties argued that the CIO was a tool for the Moon administration to shield its allies from scrutiny.

Despite the liberals’ firm push for the institution, conservatives have criticized the CIO’s investigative effectiveness, pointing out that it has made indictments in only five cases over the past four years.

Son Jun-sung, a senior prosecutor close to former Prosecutor General Yoon Seok Yeol accused of sharing drafts of criminal complaints against journalists and political figures affiliated with People Power Party Rep. Kim Woong, heads to work at the Daegu High Prosecutors’ Office on Sept. 16, 2021. [YONHAP]

The only case that resulted in a guilty verdict at the district court level involved Son Jun-sung, a prosecutor accused of delivering a criminal complaint against pro-government figures on behalf of the conservative People Power Party. However, that conviction was overturned by an appeals court last December.

“The CIO Act itself was drawn up too hastily and carelessly,” Cha Jin-a, a professor at Korea University School of Law, told the Korea JoongAng Daily, referring to the 2019 bill that fast-tracked its creation. She questioned the necessity of the CIO, arguing that it has created legal confusion by interfering with existing investigative structures.

“The current Criminal Procedure Act does not account for the CIO in its provisions,” she said.

“It only outlines the relationship between the police and the prosecution,” she added, pointing out that the interactions between the CIO, the police and the prosecution remain unresolved.

Park Se-hyun, head of the state prosecution's special investigative unit, speaks at the Seoul High Prosecutors' Office at Seocho District, southern Seoul, on Dec. 8. [YONHAP]

However, some experts believe the CIO plays a necessary role in Korea’s legal system.

Lee Yun-je, professor of law at Myongji University and one of the legal architects that created the state watchdog, told the paper that the creation of the CIO was necessary in order to counterbalance the amount of power the prosecution has over legal investigations.

“If it was like before, the investigation [into Yoon’s insurrection charges] would not have taken place at all,” he said, pointing out that the CIO’s intervention has forced investigative authorities to pursue cases they might have otherwise ignored.

Oh Dong-woon, chief of the Corruption Investigation Office for High-ranking Officials, speaks to reporters as he arrives for work in Gwacheon, Gyeonggi, on Jan. 22. [NEWS1]

Police vs. prosecution

Following the reform of investigative and prosecutorial powers, the state prosecution lost its authority to launch investigations into most major crimes, retaining jurisdiction only over corruption and financial crimes.

In January 2020, the DP passed a bill — fast-tracked the year before — to limit the prosecution’s investigative authority to six major crime categories: corruption, economic crimes, public officials, election-related offenses, the defense industry and major disasters.

During the 21st National Assembly, the DP pushed to further separate investigative rights for these crimes but ultimately compromised under fierce conservative opposition. In April 2022, the Prosecutors’ Office Act was amended, reducing the prosecution’s jurisdiction to just corruption and financial crimes.

The exterior of the Corruption Investigation Office for High-ranking Officials on Jan. 22 [YONHAP]

The amendment to the Criminal Procedure Act also stripped prosecutors of their authority to direct police investigations, instead requiring prosecutors and judicial police officers to “cooperate” on probes.

Previously, prosecutors held control over launching and exclusively finalizing investigations, while police initiated investigations but followed prosecutors as directed. Under the new system, police, which now have the authority to both initiate and conclude probes, handle initial investigations in all cases except corruption and financial crimes, with prosecutors sending the case back if additional investigations are needed.

The debate over removing prosecutorial investigative authority escalated during the Moon government, particularly amid the college admissions scandal involving former liberal lawmaker Cho Kuk, founder of the minor Rebuilding Korea Party. Cho is now serving a two-year prison sentence for his role in the scandal.

Cho Kuk, chief of the minor liberal Rebuilding Korea Party, arrives at a press conference at the National Assembly in Yeouido, western Seoul, on Dec. 12, 2024, hours after the Supreme Court upheld his conviction for fraud and interfering in a state audit. [NEWS1]

A former Seoul National University law professor, Cho gained prominence after being appointed senior presidential secretary for civil affairs under the Moon government in 2017. In 2019, Moon appointed him as justice minister and tasked him with sweeping prosecutorial reform, but Cho resigned after just one month in office amid massive public protests over allegations that he and his wife, Chung Kyung-sim, had falsified academic records to boost their daughter and son’s university admissions prospects.

The investigation into Cho and his wife was spearheaded by Yoon, who was then serving as prosecutor general. Yoon clashed with Cho over the extent of the prosecution’s investigative authority, and the probe further strained Yoon’s relationship with Moon. His ongoing battles with Moon’s next justice minister, Choo Mi-ae, ultimately pushed him to enter politics.

Yoon resigned as prosecutor general in March 2021, denouncing the Moon administration's prosecutorial reforms as "not a reform, but a serious threat to the rule of law.”

Cho’s family being indicted prompted DP supporters to further advocate for drastically pulling back the prosecutorial authority, believing the legal investigation was a targeted response against Moon's push for reforming the prosecution.

Then-former Prosecutor General Yoon Suk Yeol exits the voting booth after marking his ballot at an early voting station set up in Seodaemun District, western Seoul, on April 2, 2021, the first day of early voting for the April 7 Seoul mayoral by-election. [YONHAP]

Historical roots

Power struggles have long shaped Korea’s legal landscape, with repeated attempts to redefine the balance of investigative authority between key institutions.

The prosecution gained significant power following a fifth constitutional amendment in 1962, which explicitly granted it the authority to investigate cases, indict suspects and seek warrants. At the same time, the police also retained investigative rights but did not have the authority to seek warrants.

Tensions between the police and the prosecution have flared multiple times since then.

Late President Roh Moo-hyun, right, and Chung Mong-koo, the honorary chairman of Hyundai Motor Group, take a photo in a driving event on March 11, 2005. [YONHAP]

In 1998, scholars and politicians debated granting the police independent investigative authority. Another major confrontation arose after the election of late President Roh Moo-hyun in 2002, when then-Police Commissioner Huh Joon-young openly challenged the prosecution over giving the police an independent authority to investigate cases.

The idea of establishing the CIO dates back to 1996, when the civic group People’s Solidarity for Participatory Democracy proposed an anti-corruption initiative that included creating the authority.

The formation of a third investigative body was also a key campaign pledge of the late President Kim Dae-jung, though his efforts were ultimately blocked by the prosecution. Roh later revived the proposal, vowing to establish the institution.

Despite persistent efforts from liberal administrations, the CIO was not formally established until the Moon government, largely due to strong opposition from the prosecution.

Impeached President Yoon Suk Yeol makes a triumphant fist gesture toward his supporters as he leaves the Seoul Detention Center in Uiwang, Gyeonggi, on March 8. [YONHAP]

Yoon’s convoluted investigation

Despite being discussed for decades, the CIO faced skepticism from both political and legal circles when it was finally established in 2021.

Experts point out that the current CIO Act lacks clear legal guidelines on the office’s investigative and prosecutorial jurisdiction — an issue highlighted by the CIO’s recent attempt to launch a probe and arrest Yoon.

“The law does not explicitly state whether the CIO has jurisdiction over insurrection cases, and there are no Supreme Court rulings on the matter,” said Prof. Cha, adding that the Yoon investigation is a prime example of the “rushed passage” of the CIO bill.

“The absence of clear legal provisions has only added to the complexity of the current situation.”

Former president Moon Jae-in, center, speaks to the press during an election campaign in Ulsan on April 2, 2024. [YONHAP]

Under the CIO Act, the office has jurisdiction to investigate a range of crimes committed by high-ranking officials, including abuse of power and illegal political funding. However, Yoon’s legal defense team has argued that the CIO lacks the authority to investigate a sitting president on insurrection charges, making the investigation and arrest “unlawful.”

The impeached president, who had been detained at Seoul Detention Center in Uiwang, Gyeonggi, was released after 52 days when the Seoul Central District Court ruled that his arrest was unlawful. The court cited two main reasons: first, that Yoon had been indicted after his custody period had already expired, and second, that the CIO Act did not state whether the authority is eligible to investigate insurrection charges.

Regarding the ruling, Prof. Cha suggested that the court’s decision was an attempt “to minimize any risks” of the trial being overturned by higher courts due to legal uncertainties surrounding the arrest.

“If the higher court rules that the CIO does not have the rights to investigate insurrection charges, the trial itself may become invalid,” she said.

A person heads into the Constitutional Court in Jongno District, central Seoul, on March 7. [YONHAP]

Despite the legal disputes, Prof. Lee believes the CIO played a necessary role in the probe.

“It is true that there are clarity issues regarding the jurisdiction of the CIO,” Prof. Lee said.

“However, that was due to political mechanisms getting in the way of proper legislation that gives the CIO the clarity it needs.”

According to Lee, the problems of the CIO could have been cleared up during its formation, but the CIO legislation was caught up in an electoral compromise in the National Assembly, diminishing the watchdog’s investigative capabilities and placing its legal categorization into limbo.

“It is also important to note that the legislation had faults, including limiting its administrative staff numbers and making all prosecutors leave the office after three years.”

“Why would capable people try to work for the CIO when other institutions like the state prosecution offer life-long employment?”

Lee Jae-myung, leader of the liberal Democratic Party, left, presents a gift to former President Moon Jae-in in Moon's residence in South Gyeongsang, on Jan. 30. [DEMOCRATIC PARTY]

Under the CIO Act, prosecutors can only serve three-year terms, and the office operates with a limited workforce — just 15 prosecutors and 36 investigators. The staffing shortage became evident when the CIO failed in its initial attempt to execute a warrant to detain Yoon.

Lee stressed that the CIO’s presence made the police and prosecution fight to undertake Yoon’s investigation to gain the upper hand and an opportunity to investigate on their respective terms.

“Considering Korea's history, there is a good chance there wouldn't have been any proper investigation at all had the CIO not existed," said Lee, alluding to the prosecution's alleged record of politically motivated investigations.

Then-liberal Democratic Party presidential candidate Lee Jae-myung, left, and then-conservative People Power Party presidential candidate Yoon Suk Yeol attend a ceremony marking the 89th anniversary of the death of independence activist Yun Bong-gil at Hyochang Park in Yongsan District, central Seoul, on Dec. 19, 2021. [NEWS1]

However, Prof. Cha argued that flaws in the CIO Act and the previous administration’s push to separate investigative and prosecutorial powers ultimately contributed to the legal complexities surrounding Yoon’s case.

“If the CIO hadn’t existed, the investigation and indictment would have been handled by the police and prosecution, and Yoon’s arrest likely wouldn’t have been overturned,” she said.

Yoon, who is awaiting a ruling on his impeachment, faces a separate criminal trial on insurrection charges related to the botched martial law declaration. Following the court’s decision to revoke his arrest, the CIO stressed that the ruling does not mean its investigation was deemed “unlawful” or that the court fully “accepted the defendant’s reasoning.”

Despite the legal controversies, the CIO, currently investigating Yoon’s insurrection charges under a joint investigative headquarters system with the police, will continue its probe unless it transfers the case to other investigative authorities.

BY CHO JUNG-WOO, KIM MIN-YOUNG [[email protected]]