South Gyeongsang Province Gov. Hong Joon-pyo was questioned Friday by the prosecution in Seoul over his alleged involvement in a high-profile graft scandal, becoming the first to be questioned among eight political heavyweights mired in the case.

The bribery allegations have dealt a serious blow to Hong’s reputation as a “corruption buster” that he built while working as a state prosecutor in the 1980s and 1990s.

“I feel sorry for having caused public concern. I am here to offer my explanation (concerning the allegations against me),” Hong told reporters as he appeared at the Seoul High Prosecutors’ Office in southern Seoul.

Hong is alleged to have taken 100 million won ($93,000) from late former Keangnam Enterprises chairman Sung Woan-jong in 2011. Sung, who was found after an apparent suicide last month, left a bribery list that included Hong and President Park Geun-hye’s top aides, such as her chief of staff Lee Byung-kee.

Investigators are considering filing a charge against Hong of violating the political fund act.

Hong denied the charge.

The prosecution suspects Sung handed illicit money in a shopping bag to Hong’s secretarial staff via a former executive of the construction firm in June 2011 when Hong was running in the leadership contest of the Grand National Party, the precursor to the ruling Saenuri Party.

Investigators are examining whether Hong was aware of the money transfer to his secretary and whether Sung ever contacted Hong to talk about the provision of the illicit money.

The prosecution is also investigating the allegation that Hong’s aides tried to pressure the former executive of Keangnam Enterprise, who allegedly delivered the money to Hong’s aides, into not making unfavorable statements about Hong during a prosecutorial interrogation.

Hong also denied this allegation.

The ex-Keangnam official, identified by his surname Yoon, has already been questioned by the prosecution four times. Investigators said they have secured “circumstantial evidence” to back the allegation that Sung handed the illegal cash to Hong’s aides.

A prosecution official said the investigation into Hong’s allegations proceeded “smoothly.”

“The probe proceeded smoothly as Hong brought a considerable amount of materials to refute the allegations against him,” the official said, declining to be identified.

Political circles have carefully watched the graft investigation into Hong and seven other politicians, as the probe is expected to have a considerable impact over the political landscape, particularly ahead of the general parliamentary elections slated for April 2016.

Hong’s fall from grace is also expected to affect the ruling party’s lineup of presidential hopefuls. Hong, the former chairman of the ruling party, has long been cited as one of the party’s potential contenders for the 2017 presidential election.

Amid the ruling party’s struggle to minimize the fallout from the graft scandal, the main opposition New Politics Alliance for Democracy has stepped up its offensive against its rival party, arguing that a thorough probe into President Park’s aides, embroiled in the scandal, should be conducted.

By Song Sang-ho (sshluck@heraldcorp.com)