The corruption scandal involving former aides of Jun Byung-hun, a top adviser to President Moon Jae-in, shows how complicated Korean politics can be.

On the surface, it is a typical bribery case in which politicians and business executives traded influence and kickbacks. But the fact that it is the first time that the state prosecution has targeted a top presidential aide since Moon took office in May is stoking political speculations.

Given what prosecutors have found so far, the main suspects in the case are three associates of Jun, a former lawmaker who Moon tapped as his first senior presidential secretary for political affairs, and executives of Lotte Homeshopping.

In 2015, Jun, then an opposition lawmaker, was a member of the parliamentary standing committee overseeing home shopping businesses. Lotte, whose reputation had been tainted by a separate corruption case in the previous year, was working to obtain government approval to extend its business license.

Moreover, Jun, a critic of big home shopping businesses, was pushing for legislation to prohibit home shopping companies from unfair treatment of their suppliers and partners.

So there was a rich environment for a suspicious deal between the two sides. Prosecutors said they obtained testimonies from Lotte executives that they met Jun’s aides to seek the lawmaker’s favors regarding their business.

The aides asked the company to donate money to the Korea e-Sports Association, which Jun headed before entering Cheong Wa Dae. They demanded a lot more, but Lotte eventually provided 300 million won ($270,000). As is common with such a case, the three are suspected of pocketing about 110 million won of the sum.

As expected, Jun flatly denied any involvement in the case, saying he did nothing illegal and allegations concerning him are simply preposterous.

Whether he was telling the truth or not should be determined by a thorough investigation by the prosecution. There have already been reports that Jun’s family members used gift cards provided by Lotte.

Prosecutors should also determine whether part of the money donated by Lotte and other firms went to Jun, who exerted strong influence in the games industry.

The head of the Game Rating and Administration Committee pointed out during a parliamentary inspection of the government last month that Jun and his associates and relatives were using their influence to interfere with government regulations on the industry.

One more reason the case is drawing public attention is that it has weighty political implications. Most of all, the latest scandal comes amid a flurry of probes into past governments headed by ousted President Park Geun-hye and her predecessor Lee Myung-bak.

Moon insists that the investigations are part of efforts to address the irregularities, while critics accuse him of engaging in a ruthless political vendetta against his former political foes.

The critics’ voices have been bolstered by the death of a senior prosecutor who took his own life while prosecutors prepared for his arrest in relation to his time at the National Intelligence Service, which has become the Moon government’s prime target in its purge of former administration officials. The incident is brewing discontent even inside the prosecution.

So there is some ground to the view that the investigation of Jun’s aides is an effort by the government and prosecution to water down growing public antipathy to the harsh persecution of past government officials. There is also speculation of a power struggle inside Moon’s inner circle.

Whether there is political motivation behind the case or not, the prosecution ought to find the truth, for which questioning Jun is indispensable. It is common sense that Jun should step down from his post, which could affect the probe in one way or another.