A special counsel team investigating former first lady Kim Keon-hee began questioning a former Seoul deputy mayor and a business owner about whether Seoul Mayor Oh Se-hoon had a supporter cover the costs of his pre-2021 polling.

The team on Tuesday interrogated business owner Kim Han-jung, who is under investigation for paying for opinion polls on Oh's behalf, as well as Seoul Deputy Mayor Kang Cheol-won, who is also a suspect in the case. Both face charges of violating the Political Funds Act.

Before the interrogation, Kang denied ever asking power broker Myung Tae-kyun about the polling, and Kim claimed he had paid for the surveys and received the results but did not share the information with Oh.

Investigators suspect that Oh had Myung's firm conduct 13 unpublished polls during his campaign for the April 7, 2021, by-election.

They also say that Kim sent 33 million won, or around 22-thousand U.S. dollars, to the firm on Oh's behalf to pay for the polls.