SEOUL, South Korea (AP) — South Korean investigators on Friday again sought to question impeached President Yoon Suk Yeol over his Dec. 3 declaration of martial law, summoning him for questioning on Christmas Day despite his repeated refusal to cooperate.

The Corruption Investigation Office for High-Ranking Officials, which is leading a joint investigation with police and military authorities into the ill-conceived power grab that lasted only a few hours, said it plans to question Yoon on charges of abuse of authority and orchestrating a rebellion.

Yoon, whose presidential powers have been suspended since the opposition-controlled National Assembly impeached him on Dec. 14, has dodged several requests by the joint investigation team and public prosecutors while also blocking searches of his office.

It’s not clear what investigators can do if Yoon continues to reject their demands. Under the country’s laws, locations potentially linked to military secrets cannot be seized or searched without the consent of the person in charge, and it’s unlikely that Yoon will voluntarily leave his residence if he faces of being compelled to appear.

Yoon is focusing on defending himself at the Constitutional Court, which following his impeachment will decide whether to remove him from office or reinstate his powers.

Yoon’s martial law decree and parliamentary impeachment have triggered a political storm, disrupting state affairs, halting high-level diplomacy and sending shockwaves through financial markets at a time when the country was already grappling with a faltering economy.

The country’s acting leader, Prime Minister Han Duck-soo, and other officials have tried to reassure allies and diplomatic partners that things are returning to normal, but tensions between rival political parties are only escalating as they clash over government policies and the appointments of new justices to the Constitutional Court, which has three vacant spots.

Authorities have already arrested Yoon’s defense minister, police chief and several other military commanders involved in the attempt to enforce the martial law decree, which harkened back to the days of authoritarian leaders the country hasn’t seen since the 1980s.

Yoon and his military leadership have been accused of attempting to block parliament from voting to end martial law by sending hundreds of heavily armed troops to encircle the National Assembly. Yoon says the troops were there to maintain order.

Kwak Jong-keun, the now arrested commander of the Army Special Warfare Command, testified in parliament that Yoon had asked for his troops to “quickly destroy the door and drag out the lawmakers who are inside” the Assembly’s main chamber where the vote occurred. Kwak said he did not carry out Yoon’s orders.

Yoon has also been accused of ordering defense intelligence officials to detain key politicians, including opposition leader Lee Jae-myung, National Assembly speaker Woo Won Shik and the ex-leader of his own conservative party, Han Dong-hun, according to a high-ranking intelligence official and Han himself, a reformist who supported investigations into corruption allegations against first lady Kim Keon Hee.

The joint investigation team is also seeking an arrest warrant for Maj. Gen. Moon Sang-ho, commander of the Defense Intelligence Command, who was detained this week over suspicions that he sent troops to the National Election Commission in Gwacheon city after Yoon declared martial law.

Yoon defended his decision for troops to be deployed at the election commission as other forces were encircling the National Assembly. He claimed the troop deployment was necessary in order to investigate supposed vulnerabilities to the commission’s computer systems potentially affecting credibility of election results.

Yoon’s failure to offer any evidence in support of his claims raised concerns that he was endorsing conspiracy theories from right-wing YouTube channels that April’s parliamentary elections were rigged. The Democratic Party had won those elections by a landslide. The election commission rejected Yoon’s allegations, stating there was no basis to suspect election fraud.

Moon, the military intelligence chief, is also suspected of discussing operational plans for enforcing martial law with two subordinates and retired former defense intelligence commander Noh Sang-won at a fast-food restaurant, just two days before Yoon declared martial law.

Seok Dong-hyeon, a lawyer and spokesperson for Yoon’s legal team, defended the president’s actions on Thursday. He echoed Yoon’s assertion that he didn’t commit rebellion but saw martial law as an emergency measure to counter the main opposition Democratic Party, which used its parliamentary majority to obstruct his agenda.

Seok insisted that Yoon had no intentions to paralyze the parliament’s functions, despite the troop deployment to the National Assembly, and claimed he never ordered politicians to be detained.

When asked whether Yoon would continue to ignore authorities’ requests to question him and search his office, Seok declined to give a specific answer, saying that these matters would be handled by Yoon’s legal team, which he said has been nearly assembled.

Some experts say any attempt to compel Yoon to appear for questioning would ultimately require consent of the country’s acting leader, Prime Minister Han Duck-soo, who is locked in a standoff with the opposition Democratic Party after he vetoed several controversial agricultural bills backed by the party.