South Korean prosecutors on Thursday summoned the country’s former justice minister as they expand an investigation into corruption allegations surrounding his family that sparked huge protests.

Cho Kuk’s questioning at the Seoul Central District Prosecutors’ Office came weeks after the arrests of his wife, brother and another relative over their suspected involvement in financial crimes and faking credentials to help get Cho’s daughter into medical school and obtain scholarships.

Cho, a reformist law professor and confidant of South Korean President Moon Jae-in, resigned as minister last month, citing the burden of the investigation into his family. He has denied legal wrongdoing while apologizing over the perks his daughter is alleged to have received.

FILE- In this Oct. 12, 2019, file photo, pro-government supporters hold signs with pictures of Justice Minister Cho Kuk, before a rally supporting Cho in front of Seoul Central District Prosecutors' Office in Seoul, South Korea. The letters read "Reform the Prosecution," and "Protect Cho Kuk." South Korean prosecutors have summoned the country’s former justice minister as they expand an investigation into corruption allegations surrounding his family that sparked huge protests. (AP PhotoLee Jin-man, File)

FILE- In this Oct. 12, 2019, file photo, pro-government supporters hold signs with pictures of Justice Minister Cho Kuk, before a rally supporting Cho in front of Seoul Central District Prosecutors' Office in Seoul, South Korea. The letters read "Reform the Prosecution," and "Protect Cho Kuk." South Korean prosecutors have summoned the country’s former justice minister as they expand an investigation into corruption allegations surrounding his family that sparked huge protests. (AP PhotoLee Jin-man, File)

“I will soon be investigated by prosecutors. Everything about me will come under suspicion and I might get into trouble for things that I didn’t know about or don’t remember,” Cho wrote on Facebook on Monday. “I feel miserable, but I will invest every effort to establish the truth and restore my honor.”

Huge crowds of Cho’s supporters and critics have marched in Seoul for weeks, demonstrating how the monthslong saga has deepened the country's political divide.

Before Cho’s resignation, Moon stood firmly by the key political ally he appointed in September despite parliamentary resistance. But the controversy surrounding Cho caused the president's popularity to slide.

FILE - In this Oct. 26, 2019 file photo, supporters of the former Justice Minister Cho Kuk hold up cards showing national flags during a rally demanding reform at the prosecution service near the National Assembly in Seoul. South Korean prosecutors have summoned the country’s former justice minister as they expand an investigation into corruption allegations surrounding his family that sparked huge protests. (AP PhotoAhn Young-joon, File)

FILE - In this Oct. 26, 2019 file photo, supporters of the former Justice Minister Cho Kuk hold up cards showing national flags during a rally demanding reform at the prosecution service near the National Assembly in Seoul. South Korean prosecutors have summoned the country’s former justice minister as they expand an investigation into corruption allegations surrounding his family that sparked huge protests. (AP PhotoAhn Young-joon, File)

Prosecutors last month arrested Cho’s university professor wife, Chung Kyung-shim, who has been indicted over her suspected involvement in dubious private equity investments and faking materials to help their daughter’s admission to a medical school in Busan.