A spoils system is an indispensable part of a democracy. The problem in South Korea is that after an election, winning governments and parties take it too far, often engaging in illegal activities.

The power abuse scandal involving the Environment Ministry is a case in point. After three months of investigation, the prosecution is zeroing in on top officials, including former ministry head Kim Eun-kyung and senior presidential officials.

The case came to light thanks to Kim Tae-woo, a whistleblower who was part of the special investigation unit within Cheong Wa Dae. Both the Environment Ministry and Cheong Wa Dae officials initially denied Kim’s allegations that they had conspired to kick out executives of public corporations who had been appointed by the previous government.

But prosecutors have secured evidence, piece by piece, suggesting accused officials broke the law.

Investigators found the Environment Ministry had drawn up a list of executives of public corporations under its oversight with a view to fill posts with people close to the current government and ruling party, including members of the campaign team for President Moon Jae-in.

In the process, Environment Ministry officials put pressure on those who had been appointed by former President Park Geun-hye. Intimidation was not spared, with officials threatening audits or other means to force them out.

All these actions -- which clearly breached the law -- were aimed to pave the way for people with close ties to the Moon administration to take over the posts. Now, in the third calendar year of his five-year term, the president still has ample former campaign workers and supporters to reward.

Investigators point to the case of the Korea Environment Corp. as an example of what they see as a well-orchestrated scheme to remove people appointed by the Park government and fill their posts with new appointees.

They said Environment Ministry officials pressured the former auditor of the KEC, who took over during the Park government, to resign voluntarily.

Then they tried to fill the post with a person recommended by the presidential office. Ministry officials provided the candidate with information about the KEC and disclosed questions that would be asked during the interview. But the candidate failed to pass the first stage of the process -- evaluation of candidates on paper.

Investigators said the vice environment minister was then called in to the presidential office over the case, which indicates that senior ministry officials and Cheong Wa Dae aides worked closely together on the matter.

It is against this backdrop the prosecution sought an arrest warrant for former Environment Minister Kim Eun-kyung. Kim attended court Monday for a hearing on whether to allow her detention in relation to suspicions she abused her power and intervened in personnel affairs of public corporations.

Kim is the first former member of the Moon Cabinet to face a criminal investigation. Given that the former minister was a key member of the government of the late President Roh Moo-hyun, Moon’s former boss and mentor, the prosecution’s action seems to reflect its confidence in the evidence corroborating the former minister’s misdeeds.

In other words, the prosecution has secured enough evidence and testimony to indict the former minister and other senior officials for allegedly blacklisting people appointed by the former government and replacing them with new appointees.

In view of the gravity of the case, what the prosecution should guard against is scapegoating the former minister and letting senior presidential officials go unpunished for any role they may have played -- especially those at the personnel office of Cheong Wa Dae.

What should not be overlooked is that the Environment Ministry may not be the only government body involved in what is believed to be a governmentwide purge.

Cheong Wa Dae should cooperate with the prosecution’s investigation of presidential officials. The fact that all four major opposition parties, including progressive parties typically friendly toward Moon and the ruling party, are raising one voice calling for the thorough investigation of the Environment Ministry reflects how the public views the case.

During his election campaign, Moon severely criticized the Park government for blacklisting cultural and arts figures, an action that resulted in jail time for a former Cheong Wa Dae chief of staff and culture minister.

What the Environment Ministry and Cheong Wa Dae allegedly did to executives of public corporations under the ministry’s oversight constitutes no less serious a crime. In all, the spoils system in this country has gotten spoiled.