Song Young-gil, a former leader of the main opposition Democratic Party (DP), filed a complaint against President Yoon Suk Yeol on Tuesday, accusing him of making false statements about a fraud case involving his mother-in-law during last year's presidential campaign.
The mother-in-law, Choi Eun-soon, was imprisoned Friday after an appeals court upheld her one-year prison sentence for forging a financial document used in a land purchase deal.
During the election campaign, Yoon publicly denied any wrongdoing on her part, asserting that she had been deceived by the other party for an amount of around 5 billion won (US$3.91 million).
"As President Yoon's mother-in-law has been detained, it is common sense for the president to reflect on his lies and issue an apology," Song said in a news conference in front of the Seoul Central District Prosecutors Office.
He lodged a complaint against Yoon on charges of violating the laws on elections and political parties.
The prosecution is not expected to immediately launch an investigation into Yoon, as the Constitution grants the president immunity from criminal indictment during his tenure, except in cases of insurrection or treason.
Even if charges against the president are discovered, the indictment will be suspended until the end of his term.
The 76-year-old Cho has been found guilty of forging a bank balance certificate, making it appear as if she had deposited 34.7 billion won and using it to purchase a piece of land in Seongnam, south of Seoul, in 2013.
In the initial trial, she was sentenced to one year in prison but was not detained. On Friday, the Uijeongbu District Court dismissed her appeal and ordered her imprisonment.
Song himself is embroiled in a cash-for-votes scandal involving his allies during the party's 2021 leadership election, in which he was elected chairman. Although he has denied any involvement, the prosecution is likely to summon him soon for questioning.
Source: Yonhap News Agency