Minor Rebuilding Korea Party leader Cho Kuk appeared for the prosecution's questioning in their investigation into allegations that former President Moon Jae-in's previous son-in-law was unfairly hired as an airline executive in exchange for favors to the company's founder.

Prior to the questioning at the Jeonju District Prosecutors' Office on Saturday, Cho, a presidential aide and justice minister under the Moon government appearing as a witness, accused the investigative agency of targeting the former president in their probe the past three years.

The minor party chief also questioned the prosecution's motive, suggesting the investigation against Moon and his family could be an attempted deflection of allegations surrounding President Yoon Suk Yeol and First Lady Kim Keon-hee.

Prosecutors suspect that budget carrier Thai Eastar Jet's hiring of Moon's then-son-in-law identified by his surname Seo, was linked to the appointment of Lee Sang-jik, the founder of Eastar Jet who also established the Thai airline, as head of the Korea SMEs and Startups Agency in 2018.

The state agency is expected to question Cho regarding allegations that then-presidential aides, including Cho while serving as the senior presidential secretary for civil affairs, had nominated Lee for the SMEs agency post during a closed-door meeting in late 2017.

Earlier on Friday, the prosecutors raided the Seoul residence of Moon's daughter regarding allegations that the former first couple had illegally provided financial assistance to their daughter.