Yang Hyun-suk, the founder and former head of YG Entertainment, was questioned by police for nine hours over allegations of procuring prostitution, the police said Thursday. Prostitution is illegal in South Korea.

According to the police, Yang was summoned to the investigation unit of the Seoul Metropolitan Police Agency at around 4 p.m. Wednesday and was questioned until 45 minutes past midnight.

Yang is suspected of arranging prostitution during a July 2014 meeting with foreign investors at a high-end restaurant in Seoul. He denied the allegation, claiming that while he was invited to the dinner, he was unaware of prostitution taking place.

Psy, who was present at the meeting, faced police questioning Monday in a related probe. The singer also denied involvement in the alleged procuring of prostitutes.

In a press briefing Monday, the police agency said it had yet to find evidence to substantiate the charges against the K-pop mogul.

Yang stepped down from all posts he held at YG Entertainment on June 14, following a whistleblower report that the agency colluded with police to cover up a drug offense suspicion involving one of its artists. His brother Yang Min-suk, who served as the agency’s CEO, also resigned the same day.

By Kim Arin (arin@heraldcorp.com)