A joint investigation team made the request to a Seoul court a day after Yoon didn’t appear for scheduled questioning by the Corruption Investigation Office for High-ranking Officials for the third time. The previous two summons were for Dec. 18 and Christmas Day.

South Korea is experiencing one of its most tumultuous periods in years after Yoon’s short-lived imposition of martial law on Dec. 3, which led to his impeachment and subsequently that of Prime Minister Han Duck-soo, who briefly served as acting leader. The political chaos is compounded by the country’s worst civil aviation accident after a Jeju Air flight crashed on Sunday, killing all but two of the 181 people on-board.

A court will determine whether to issue the arrest warrant for Yoon, though it’s not clear when that decision will be made. If granted, he would be the first sitting president in the country’s history to be arrested while still in office. 

Yoon’s lawyer submitted a statement to the court saying the investigation team has no legal basis to seek a warrant for the president. The lawyer declined to comment who should lead the probe when asked by reporters on Monday.

Even if the court issues the warrant, it’s uncertain if the investigators would manage to take the president into custody. A previous attempt by the police to search the presidential office was blocked by Yoon’s office.

The president’s decision to repeatedly avoid questioning and challenge the investigators’ authority appears aimed at delaying the proceedings against him, said Lee Chang-hyun, a law professor at Hankuk University of Foreign Studies.

Yoon has vowed to keep defending himself, signaling his intent to fight in court to stay in office and insisting that his martial law decree was within his constitutional powers. Meanwhile, a trial is ongoing to decide whether to reinstate or permanently remove Yoon from office. It has until June to make a decision, and the next hearing is scheduled for Jan. 3.

The South Korean won initially weakened on Monday following the deadly plane crash, but later rose 0.2% against the dollar to 1,468.05, buoyed by a gain in local stocks and pledges from authorities to stabilize the markets.

Finance Minister Choi Sang-mok, who became acting president Friday after Han’s impeachment, is facing a major test just two days into the job. He has declared a week-long mourning period till Jan. 4 after the plane crash, called for a strict investigation into the incident and ordered an emergency safety inspection of the entire airline system.

Han was impeached for refusing to meet the opposition party’s demand to immediately appoint three judges to fill vacancies on the nine-member Constitutional Court, a move that would likely increase the chances of upholding Yoon’s impeachment. Citigroup expects Choi to quickly fill those positions to ease uncertainties, it said in a report Monday.