Police will question a local contractor and other key figures allegedly involved in a snowballing sex-for-favors scandal.

The construction firm executive is suspected of arranging banquets and sexual services for high-ranking officials and public figures in return for their influence.

Officials at the National Police Agency said Wednesday that they summoned three witnesses overnight and secured statements on the businessman’s illegal lobbying activities and secretive meetings.

“We have secured the necessary testimonies from the three witnesses,” an investigator said. 

The 51-year-old man surnamed Yoon is accused of filming officials and others having sex with women he hired for the purpose. Sources say that he might have used the footage to blackmail the officials for business favors.

The police said they would also question those influential figures mentioned by the witnesses on Thursday if possible and investigate whether they peddled their influence for Yoon to win construction contracts.

Investigators will also summon women who were reportedly hired by Yoon for sexual services for questioning. Officials added that they would also focus on securing the videos, reportedly filmed by Yoon, saying they could not yet confirm their existence.

“The existence and the whereabouts of the videos is (our) urgent interest,” an official said.

The scandal sent shockwaves around the country early this week as it reportedly involves a number of influential figures including an official who serves in a vice ministerial post and the head of a general hospital.

The ruling Saenuri Party urged the police to thoroughly investigate the case.

“If the police try to scale down or cover up the case because it (allegedly) involves (a) high-ranking official, the police will lose its authority and the people will be outraged,” said Saenuri spokesman Lee Sang-il.

Local reports claimed that Yoon hired about 10 women, including a housewife, a businesswoman and a musician, to perform sexual services for officials. They were allegedly often invited to Yoon’s luxurious country house in Wonju, Gangwon Province or karaoke sessions between 2008 and 2011. Actresses and models were also invited to parties at the house, reports quoting neighbors said.

The case came to the attention of police after a woman filed a complaint against Yoon and his colleague for rape and extortion late last year. The woman surnamed Kwon told police that her assistants found a number of CD-ROMS in a car she had lent Yoon that showed big name officials and women having sex. The police asked Kwon to submit evidence to back up her claims but she said she had destroyed the discs. The prosecution dropped all charges against Yoon last month aside from one relating to an unregistered air gun.

Kwon claimed that she had lent Yoon 1.5 billion won ($1.34 million) in cash and that he had threatened to release another video of him raping her while drugged after she asked to be repaid.

By Cho Chung-un (christory@heraldcorp.com)