As Korea reshapes investigative powers, Jang Yun-gi case exposes oversight concerns 

As reports broke out that the father of Jang Yun-gi, who is accused of fatally stabbing a high school student in Gwangju, allegedly attempted to destroy evidence, it fueled the discussion over how investigative agencies should be monitored, as Korea is in the midst of another overhaul of its criminal investigation system.

The National Police Agency's special investigation team questioned a former head of the criminal investigation division at the Gwangsan Police Station in Gwangju, who oversaw the original investigation into the Jang case, as a witness, according to police on Sunday.

Investigators are examining whether senior officers involved in the case improperly intervened in the probe into allegations that Jang's father, a serving police officer, tampered with evidence.

The revelations have reignited concerns over long-running efforts to redefine the division of investigative authority between the police and prosecutors, amid renewed allegations of botched investigations and preferential treatment by the police.

A 70-year debate over investigative powers

The debate over investigative powers dates back to the establishment of Korea's modern criminal justice system after liberation from Japanese colonial rule (1910-45).

During the colonial period, the police exercised sweeping authority, handling investigations, prosecutions, trials and even the execution of criminal sentences. It was not until the 1960s that constitutional safeguards were introduced, including a provision guaranteeing the political neutrality of the police and granting prosecutors exclusive authority to request arrest warrants.

The prosecution's influence expanded further during the 1990s as it led a series of high-profile investigations involving major conglomerates and politicians.

The debate over police-prosecution reform accelerated under the Moon Jae-in administration, from 2017 to 2022, which pursued a policy aimed at stripping prosecutors of virtually all investigative powers.

The government abolished prosecutors' authority to direct police investigations and limited their direct investigative powers to corruption and major financial crimes.

The subsequent Yoon Suk Yeol administration partially reversed those changes by expanding prosecutors' investigative authority through revisions to enforcement regulations. 

After the Dec. 3, 2024, martial law crisis and the inauguration of the Lee Jae Myung administration in June 2025, however, the ruling Democratic Party passed amendments to the Government Organization Act abolishing the Public Prosecution Office and creating two new agencies: the Supreme Prosecutors’ Office and the Serious Crimes Investigation Agency.

Questions over whether police can police themselves

The latest controversy has also raised broader questions about whether the police, now numbering more than 130,000 officers, can effectively police themselves.

Disciplinary actions against police officers rose from 426 cases in 2020 to 528 last year after police-prosecution investigative reforms took effect in 2021, according to National Police Agency data.

More than 300 disciplinary cases had already been recorded by June this year, putting the annual total on pace to exceed 600.

Last year, the most common grounds for discipline were violations of service regulations, including drunk driving, with 235 cases, followed by misconduct damaging the dignity of the police, including sexual misconduct, with 218 cases. There were also 27 cases involving officers accepting money or valuables including in exchange for investigative favors.

Some legal experts argue that these problems reflect structural weaknesses within what is often described as Korea's “giant police force.”

As of last year, the authorized strength of the police stood at about 131,000 officers, roughly 57 times the statutory number of prosecutors, which is capped at 2,292. 

With such a large organization, they say, effective internal oversight becomes increasingly difficult.

“The Burning Sun case and the Jang Yun-gi case show that if the police collectively decide to downplay or cover up a case from within the organization, it becomes extremely difficult to control,” said Cha Jin-a, a law professor at Korea University's School of Law. The Burning Sun scandal was a high-profile criminal case involving allegations of police corruption, sexual crimes and drug offenses linked to the Seoul nightclub Burning Sun.

Debate over how to move forward

Debate over prosecutorial investigative powers continues, with critics arguing that the ruling party's plan to abolish prosecutors' supplementary investigative authority would further weaken oversight.

In Jang's case, prosecutors' supplementary investigation in May uncovered evidence that Jang's father had personally disposed of evidence.

In another case involving the death of film director Kim Chang-min following an assault in October last year, prosecutors' supplementary investigation resulted in the charges being upgraded from fatal assault to murder.

Kim Woo-suk, a lawyer at law firm Myungjin Law and a former prosecutor, said supplementary investigations are a core safeguard against flawed police investigations.

“The essence of the prosecutorial system is to review whether police investigations were unlawful or insufficient,” Kim said. “Most supplementary investigations involve crimes affecting ordinary people and socially vulnerable victims. It makes little sense to abolish that authority simply because prosecutorial power was abused in a handful of politically sensitive cases.”

Others argue that the focus should instead be on creating effective external oversight mechanisms for investigative agencies. They say that even if prosecutors' supplementary investigative authority is abolished, potential side effects could be mitigated through meaningful oversight mechanisms, such as independent investigative review officers and investigative review committees.

“If you can’t trust the police, can we trust prosecutors?” Park Se-hee, a lawyer at Law Firm Min, said. “Even without prosecutors, independent review officers or investigative review panels could provide checks and balances. What matters is establishing a robust oversight system.”

Legal scholars also warned that protecting citizens' fundamental rights should remain the central objective of any reform.

“The debate has shifted from how to prevent abuses of prosecutorial power to simply deciding what powers should be taken away from prosecutors,” said Park Chan-un, a law professor at Hanyang University. “The political focus has been on abolishing the prosecution while paying little attention to how those changes could affect citizens during criminal investigations.”

“To protect people's fundamental rights, we should be discussing how investigative agencies should be supervised and how checks and balances between institutions should be designed,” he said.

BY OH SAM-GWON, KIM CHANG-YONG   [[email protected]]