President Yoon Suk Yeol examines a memo during the fourth impeachment trial at the Constitutional Court in Jongno District, Seoul, Jan. 23. Yonhap

A Seoul court again Saturday turned down the prosecutors' request for an extension of President Yoon Suk Yeol's arrest, prosecution officials said.

The Seoul Central District Court retained its earlier decision that rejected the first request to extend the impeached president's detention, citing "similar grounds" as the previous day's decision, a prosecution official said.

The special prosecution team had filed a new request with the court for the extension of the warrant until Feb. 6, but the court turned it down, saying it saw little need for the prosecution to "supplement" the investigation that has been led by the anti-corruption agency.

The Corruption Investigation Office for High-ranking Officials (CIO) transferred the case to the prosecution earlier this week, as the agency does not have a legal mandate to indict a president.

Requesting the extension, prosecutors have cited the need to continue the investigation, including in-person questioning of Yoon, as the president has mostly refused to cooperate with the probe.

The court' rejection leaves the prosecution having to decide whether to indict him before it has to release him by Monday. It is highly likely that the prosecution will indict the president Sunday.

Law enforcement agencies are investigating Yoon over allegations he was the mastermind behind the Dec. 3 martial law imposition that has plunged the country into a political crisis.

Yoon is looking at possible charges of insurrection and abuse of power by allegedly colluding with then Defense Minister Kim Yong-hyun and others to start a riot by declaring martial law and by sending troops to the National Assembly to stop lawmakers from voting down the decree.

Yoon has been incarcerated at the Seoul Detention Center in Uiwang, south of the capital, since his formal arrest on Dec. 19.

A Constitutional Court trial is also under way to determine whether to uphold or dismiss his impeachment by the National Assembly.

While Yoon has appeared for his impeachment trial at the top court, his legal team has argued that the CIO's investigation against him is legally flawed, calling for Yoon's immediate release.

"The CIO's investigation itself is illegal and fundamentally null and void," Yun Gap-geun, his lawyer, told reporters in a press briefing earlier in the day. "It's best that they stop all attempts to bring down the president."
Yoon's legal team issued a separate statement following Saturday's court decision, urging the prosecution not to proceed with the indictment.

"The prosecution's extension request is an admission of the inadequacy of the CIO's investigation," it said. "The prosecution should keep in mind that if they go ahead with the indictment, they will bear full responsibility for all consequences that will follow, along with the CIO." (Yonhap)