A scandal involving the manipulation of online public opinion is engulfing the political arena, with suspicions snowballing over who masterminded it.

The scandal began in January with the ruling Democratic Party of Korea requesting police investigate a remarkable surge in the number of recommendations for an article critical of the government on a popular portal site.

Two months later, three people were arrested. Unexpectedly, they turned out to be members of the ruling party. Both ruling and opposition parties were thrown into confusion.

After analyzing mobile phones used by the main suspect surnamed Kim, police found that he had contacted Rep. Kim Kyoung-soo, a ruling party lawmaker close to President Moon Jae-in.

With suspicions mounting, Kim Kyoung-soo called a press conference twice to say that he and the suspect Kim know each other but that he had nothing to do with the incident.

Circumstantial evidence suggests that the manipulation of online public opinion may have been done systematically.

The suspect Kim set up a “ghost” publishing company. Witnesses said they saw dozens of people work in the company. Police confiscated about 170 mobile phones there. The company has never published a book, but had four employees. It rented three stories of a building and paid 5 million won ($4,670) in rent on time.

The main opposition Liberty Korea Party suspects that the incident involved big shots in the ruling camp and has vowed to seek an investigation by a special counsel.

The Democratic Party drew the line between Rep. Kim and the incident, saying “it is a case of personal deviation unrelated to the party, and raising suspicions about Rep. Kim is a witch hunt.”

The suspect Kim bragged in an internet chat room for an online community he ran that he had recommended some members of the community as candidates for the consul-general in Osaka, Japan, and a Cheong Wa Dae official post.

Rep. Kim recommended a lawyer that the suspect Kim had recommended to the presidential office, which did not appoint the lawyer as the consul-general. After this, the suspect Kim is said to have fallen out with Rep. Kim and sent threatening messages to the latter.

But as for the recommendation for a Cheong Wa Dae post, police have not answered some questions: Who did Kim recommend and what has become of his recommendation? Rep. Kim also did not elaborate on the matter.

The suspect Kim campaigned online for Moon last year and sent Rep. Kim messages through the messenger app Telegram from November 2016 to last month. This arouses reasonable suspicions that he may have manipulated public opinion during the campaign.

Seoul Metropolitan Police Agency Commissioner Lee Ju-min told reporters that Kim sent messages to Rep. Kim unilaterally and that Rep. Kim rarely opened the 115 messages containing about 3,000 article links that Kim sent to a password-protected chat room.

His remark suggests a preconceived notion that the lawmaker is innocent. Police have not interrogated Rep. Kim after arresting the suspect Kim and his two accomplices on March 25.

The prosecution must not leave loose ends in its investigation. They should look into suspicions raised by the media and opposition parties regarding the possibility of organized political maneuvering. Police reportedly found a chat room where the suspect Kim conversed with politicians other than Rep. Kim.

A case involving a figure close to the president should not leave room for disputes over the partiality of investigation.

The prosecution must find the truth about whether the suspect Kim made enough contributions to Moon’s campaign to the extent that he could recommend his acquaintances as candidates for senior posts or whether he was just a political broker seeking to benefit through voluntary campaigning.

Manipulating the number of recommendations for news articles on portal sites distorts public opinion and a grave criminal act that threatens the foundation of democracy.

The Democratic Party and Rep. Kim must know that the fastest way to clear suspicions is to be transparent. They had better not try to close the case carelessly and move on, as people are watching. If the prosecution and police investigate the case passively, it will follow the same bad pattern as before that has been censured by the people. Then an investigation by a special counsel will be inevitable to clear suspicions.