Lee Yong-wook of the National Maritime Police Agency says he was employed by the Semo Marine Shipbuilding Company from 1991 to 1997.
Semo Marine went bankrupt in 1997 and was owned by Yoo Byung-eun who is at the center of a corruption scandal.
A joint team of prosecutors and police officers are currently investigated charges against Yoo and his family which include embezzlement, tax evasion and bribery.
Lee had been acting as the director of the Korea Coast Guard's police investigation unit but has since been reassigned in light of the apparent conflict of interest.
The former investigative chief admitted he had been introduced to Semo Marine after joining a religious group in the 1980's reportedly led by Yoo.
Lee said that he had broken off all contact with Semo and the group when he joined the Coast Guard in 1997.
Meanwhile, prosecutors grilled Song Kook-bin, the CEO of the company Dapanda, for over 14 hours yesterday as part of their growing investigation into the Sewol ferry's operator and its owner.
Prosecutors suspect Song was deeply involved in alleged crimes committed by Yoo Byung-eun - the de facto owner of Cheonghaejin Marine.
The prosecution says it has also summoned Yoo's second son and two daughters for questioning tomorrow morning at 10AM, while Yoo is reportedly expected to be appear before authorities by the end of this week.
For tbs eFM News, I'm Paul Yi.■
Providing news and Press Releases provided tbs / copyright © tbs. Unauthorized redistribution prohibited rants