Hyosung Group Chairman Cho Hyun-joon returned home early Thursday morning after being grilled by prosecutors for around 20 hours over allegations that he set up a slush fund worth ten billion won, or nine-point-three million U.S. dollars

A team of prosecutors at the Seoul Central Prosecutors' Office said they let the business mogul go home at around 5:30 a.m. Thursday after questioning him from 9:30 a.m. the day before. Cho is said to have denied the allegations against him.

The chairman is suspected of having set up a secret fund of about ten billion won through a paper company run by an associate called Hong from 2010 to 2015, transferring money through Hyosung Group's construction department.

Before Cho appeared before the prosecution, Hyosung Group claimed that the slush fund allegation was mere conjecture. 

Prosecutors said they will carefully scrutinize Cho's statement before deciding whether to request an arrest warrant for the chairman.