It is extremely rare for a prosecutor to detain an incumbent prosecutor suspected of committing a criminal offense. The usual practice is for the prosecution to take the process of receiving a letter of resignation from a prosecutor involved in a criminal case before arresting him. Such a process supposedly helps both the prosecution and the errant prosecutor save what little face they have left.

On Monday, however, a special prosecutor arrested an incumbent prosecutor, Kim Kwang-joon, who is suspected of taking a total of 900 million won from the mastermind of a fraudulent pyramid scheme and the business group Eugene in exchange for influence peddling. He is also suspected of taking smaller sums of money in bribes from others.

But there was no mention that the prosecution demanded a letter of resignation from the errant prosecutor before arresting him. Nor was there any talk that the prosecutor offered to resign ahead of his arrest. Did the case generate so much public distrust of the prosecution that it was convinced that a letter of resignation from the prosecutor would be of little help this time?

Probably, it was. The bribery case was so devastating to the prosecution’s public relations that Prosecutor-General Han Sang-dae had to make a public apology over his arrest. He acknowledged his office deserved a severe reprimand from the public. Then he promised that the special prosecutor in charge of the high-profile case would leave no stone unturned before closing his investigation.

As a follow-up measure, the prosecutor-general has summoned senior prosecutors to a conference on Thursday to strengthen internal checks on errant prosecutors and a wider reform on the law-enforcement agency. Yet, it should not come as a surprise to the prosecutor-general if the general public and the political community are found to have no high expectations about the conference.

It was not prosecutors, but the police that started an investigation into the case. It apparently shamed the prosecution. The case was thrown into the spotlight when the prosecution snatched the investigation from the National Police Agency, with which it had long been at loggerheads over the agency’s demand to share the authority to investigate criminal cases.

To make matters worse for the prosecution, the dispute between the two law-enforcement agencies came to a head at a time when it was made public that the prosecution turned a blind eye to the first family and some Presidential Security Service officers when it was investigating a case involving them.

When it closed an investigation into the purchase of land for President Lee Myung-bak’s retirement home in June last year, the prosecution decided not to file criminal charges against any of those involved in the case. In the face of a public uproar, the National Assembly subsequently passed a law on the appointment of an independent counsel empowered to look into the case again.

Wrapping up a month-long investigation last week, the independent counsel notified the National Tax Service that the president’s son evaded taxes in connection with the land purchase. He also indicted the three security officers on criminal charges of misappropriation.

The action taken by the independent counsel was nothing short of a slap in the face to the prosecution, which had yet to refurbish its public image as an agency that had been used by the nation’s military-backed dictators as a tool for suppressing human rights.

The prosecution has promised time and again in the past to improve its public image by strengthening internal supervision. As evidenced by the independent counsel’s latest findings, however, the prosecution is still biased in favor of the powerful in enforcing the law. No wonder the prosecutor-general sounded hollow when he made a similar promise again this time.

A better idea is to subject the prosecution to outside checks. In this regard, major presidential candidates propose to create a new law-enforcement agency empowered to investigate criminal cases involving prosecutors as well as other powerful people such as lawmakers and cabinet members and indict the ones suspected of breaching the law.

No harm will be done if the prosecution shares its near exclusive right to file criminal charges with a new agency. Nor will it do any harm if the prosecution is made to share the investigation authority with police to a greater extent.