Jeong Jin-sang, a vice chief of staff to the Democratic Party of Korea chairman Lee Jae-myung who is regarded as one of Lee's alleged two closest confidants, was detained by the prosecution Saturday.

He is suspected of accepting 140 million won ($103,000) in bribes on six occasions from February 2013 to October 2020 from a small party of speculators including Kim Man-bae and Nam Wook in return for giving them an array of favors that enabled them to make astronomical returns from investing in an urban development project in Daejang-dong, Seongnam, Gyeonggi Province.

When Lee was elected Seongnam mayor in 2010, Jeong was appointed as chief of policy bureau of the city. When Lee was elected as Gyeonggi provincial governor in 2018, Jeong was appointed as policy adviser of the provincial office.

Jeong is also suspected of getting a promise to receive a 24.5 percent equity in Kim Man-bae's company after it was chosen as manager of the Daejang-dong project.

Jeong allegedly agreed with two other key players of the scandal -- Kim Yong, another close confidant of Lee's and vice president of the Institute for Democracy, a think tank of the Democratic Party, and Yoo Dong-gyu, a former executive of Seongnam Development -- to divide up the equity, which amounts to 42.8 billion won after taxes. The corporation affiliated with Seongnam managed the project on the city side.

Kim Yong was a Seongnam city councilor at the time of the Daejang-dong project. He also worked as spokesperson of Gyeonggi Province when Lee was its governor. He was indicted on Nov. 8 on charges of accepting 847 million won in bribes from the Daejang-dong speculators on four occasions from April to August last year. The prosecution suspects that the money was used to fund Lee's run in the Democratic Party's presidential primary. Kim Yong is also in detention.

Jeong's arrest has different meaning and impact from those of the others involved in the Daejang-dong scandal. Jeong is not only one of Lee's closest confidants, but he was a policy decision maker prior to Seongnam mayor Lee, on the path of approval at the city government at the time of the Daejang-dong development.

Jeong signed important documents on the project before Lee's final approval. It would be absurd if Lee argues that he knew little about the documents when he approved them.

Jeong strongly denies charges, but the court's issue of arrest warrant implies that suspicions are judged reasonable to some extent.

The Democratic Party argues that the charges against Jeong and Kim Yong were based only on other suspects' statements, but confessions to the prosecution by Yoo and Nam that Nam raised money for bribery and that Yoo conveyed it to Kim Yong and Jeong are said to be detailed and specific.

Jeong is said to have gotten along very well with Lee, who once said "those who can be as close to me as Kim Yong or Jeong Jin-sang deserve being called my confidants." Lee is said to have discussed almost everything with Jeong.

The prosecution reportedly regards Jeong and Lee as bound together by a "common political fate." This means they acted politically like one body and that if Jeong was implicated in a political fund offense, Lee could hardly be free from it.

The Democratic Party has reacted strongly against Jeong's arrest, denouncing the current regime for maneuvering to destroy the opposition party through the "prosecution's tyranny."

After Jeong's detention, Lee posted on a Facebook page, "If gun smoke clears, truth will reveal itself. The truth won't sink no matter how much is manipulated."

But the arrest warrant for Jeong was issued by the court after a pre-trial detention hearing that lasted more than eight hours. Few would buy an argument that the prosecution manipulated its investigation and deceived the court.

Lee's mention of investigation manipulation seems to be an attempt to mislead the people. If investigations are manipulated as he argues, he may well show evidence and cooperate actively with investigation when summoned. The investigation is nearing its end.