Former South Korean President Moon Jae-in and first lady Kim Jung-sook attend a ceremony to commemorate the fifth anniversary of the Sept. 19 Pyongyang Joint Declaration at 63 Building in Yeongdeungpo-gu, Seoul, on Sept. 19, 2023. (Herald DB)

Prosecutors are reportedly investigating the bank accounts of former President Moon Jae-in and his wife in connection with allegations that his son-in-law received an unfair advantage in being hired by an airline company.

According to legal sources Friday, the Jeonju District Prosecutor's Criminal Division 3 recently executed a search warrant to trace the financial accounts of former President Moon Jae-in and his wife Kim Jung-sook. This comes about four years after a complaint was filed against them over the hiring of their son-in-law.

Prosecutors are reportedly trying to determine the extent to which the former president and his wife provided financial support to their daughter's family.

Surnamed Seo, Moon's son-in-law has been interviewed as a witness three times this year but has refused to testify in each case. Prosecutors are considering changing Seo's status to that of a suspect.

In September 2020, the People Power Party, then the main opposition party, filed a complaint to prosecutors over Seo's employment as managing director of Thai Eastar Jet Airline, a low-cost carrier founded by former lawmaker Lee Sang-jik.

Lee had been appointed head of the government funded Korea SMEs and Startups Agency in March 2018 shortly before Seo joined Eastar's Thai unit that July.

Seo having no experience in the airline industry, and his hiring at a time the company was struggling with poor performance, sparked questions over whether the presidential office was involved in Seo's hiring at the airline.

The prosecution believes that former Moon and his wife had been supporting their daughter's family for some time, but stopped doing so after Seo was hired by Thai Eastar Jet. If the support was cut off after Seo's employment, the prosecution believes that the support from the airline, including Seo's salary and housing, could be seen as a bribe to Moon.

Prosecutors are also looking into the transfer of about $50,000 in Korean and Thai currency from Moon's daughter to a Blue House security officer.

Since the filing of the complaint, prosecutors have been investigating whether there was any quid pro quo between Lee's appointment and Seo's employment at the airline.

“Based on the court-issued warrant to trace the account, we are carefully investigating with a minimal scope to establish the substantive truth,” a prosecutor said. "It is difficult to disclose the progress of other investigations.”