Impeached President Yoon Suk Yeol who was arrested by the Corruption Investigation Office for High-Ranking Officials on charges of leading an insurrection, headed to Seoul Detention Center in Uiwang, Gyeonggi Province, Jan. 15, after completing his first day of questioning. Yonhap

The anti-corruption agency investigating impeached President Yoon Suk Yeol's martial law case is "nearly ready" to file for a warrant to formally arrest him, an official said Friday.

The Corruption Investigation Office for High-ranking Officials (CIO) is "highly likely" to file the warrant with the Seoul Western District Court, the CIO official told reporters during a press briefing, before a 48-hour deadline expires Friday night.

The CIO's decision comes after Yoon again refused to appear for questioning over his failed martial law bid Friday, the third day of his detention.

The CIO had ordered him to appear for further questioning at 10 a.m. after he failed to appear the previous day, citing health reasons.

"The president will not appear at the CIO today," Seok Dong-hyeon, Yoon's lawyer and longtime friend, told Yonhap News Agency. "He thoroughly stated his basic position during the CIO's questioning the first day and doesn't see any reason or need to respond to a question-and-answer type of interrogation."

Yoon has been held at a detention center since Wednesday night after investigators apprehended him at his residence and brought him to the CIO office in Gwacheon, just south of Seoul, to undergo over 10 hours of questioning.

Yoon filed a request with the Seoul Central District Court to review the legality of his detention, but the court dismissed the challenge Thursday night, keeping him in custody. (Yonhap)