Ko, who used to work with Choi Soon-sil, was arrested Tuesday over a number of allegations including one that he received some 20 million won ($17,400) from an official at the Incheon-based customs office in exchange for exerting influence on the agency's personnel management.

Prosecutors asked the Seoul Central District Court to issue a warrant to formally arrest Ko. The court will hold a hearing later in the day on the decision.

Ko, who made some clothing items and bags for Park, revealed the controversial relationship between Park and Choi last year, claiming that Choi received and edited the ex-president's speeches in advance. Choi had no policy experience nor did she hold any official post in the Park administration.

While Ko was praised by some as a whistleblower, others raised suspicions that he made the revelations to gain control of a company owned by Choi. (Yonhap)