A joint investigative body was formed on Wednesday to investigate President Yoon Suk Yeol's short-lived declaration of martial law, amid concerns over overlapping investigations into the high-profile case that deals with allegations of insurrection of a sitting president.

The Korean National Police Agency's National Office of Investigation said it would work together with the Corruption Investigation Office for High-ranking Officials and the Defense Ministry "to leverage the strengths of each institution and eliminate confusion and inefficiencies." The joint team excludes the prosecution which has been competing with the police and the CIO to take the lead in the insurrection investigation.

The police previously declined the prosecutors' request for a joint investigation last week.

The announcement comes hours after the police arrested Korea National Police Agency Commissioner Cho Ji-ho and Seoul Metropolitan Police Agency Head Kim Bong-sik without a warrant on charges of insurrection early Wednesday, detaining the top two police officials simultaneously for the first time. Both officials were placed under a travel ban as of Tuesday.

The police officials were placed under emergency arrest at 3:50 a.m. following lengthy interrogations lasting up to 11 hours for Cho and 10 hours for Kim.

Both Cho and Kim are accused of directing police officials to block access to the National Assembly when martial law was declared on Dec. 3 to prevent lawmakers from entering the parliament to repeal the martial law decree. Cho is also suspected of sending police personnel to the National Election Commission to assist the military in carrying out orders issued under martial law.

A police official told Yonhap News Agency that the emergency arrests were made considering that insurrection charges are “serious offenses which are punishable by death” and because there were “concerns regarding the possibility of evidence tampering.”

Through additional investigations, police officials plan to decide whether to request arrest warrants for Cho and Kim. Both chiefs will be released if such warrants are not filed or granted within 48 hours.

With both leading police officials absent for the time being, Lee Ho-young, the Deputy Commissioner of the KNPA, will serve as the acting commissioner, while Choi Hyun-seok, the Chief of the SMPA’s Life Safety Division, will take over as the acting head.

Later in the morning, police officials attempted to raid the presidential office by dispatching 18 investigators to secure records related to the Cabinet meeting before martial law was declared in early December. They withdrew the seizure attempt at around 7:40 p.m., as the Presidential Security Service did not permit law enforcement from entering the presidential office under the Criminal Procedure Act. Normally, authorities are permitted to execute the warrant within one week of it being issued.

According to a police official, the Presidential Office voluntarily submitted “very limited” documents and materials to the police, with other supporting documents to be submitted later. The police were unable to confirm exactly what kind of documents they were expecting and by when. The official added that the team of investigators will not make a second attempt in the future, as Yoon’s office agreed to voluntarily hand in evidence.

With a search and seizure warrant listing Yoon as a suspect under allegations of rebellion and insurrection, a police official added that the scope of the investigation includes the Cabinet meeting room, the Presidential Secret Service, the 101 Security Division of the national police and the Joint Chiefs of Staff headquarters, which is located next to the Presidential Office. The JCS building also housed the operational headquarters for the martial law troops on Dec. 3.

Police officials said Wednesday’s emergency raids were conducted at the Korean National Police Agency, the Seoul Metropolitan Police Agency and the National Assembly Guards.

Although the police obtained a seizure warrant, they were at least initially prevented from entering the presidential office due to a procedural oversight. Police officials are required to meet with a relevant presidential office representative to formally execute the warrant, but they could not, they told reporters.

Additionally, a Presidential Office official stated that it is responding to the police's search and seizure attempt "based on laws and precedents established during previous administrations" and that the office isn't "refusing the search and seizure attempt."

Whether Yoon was inside the presidential office when investigators arrived to conduct the raid Wednesday morning was unknown.

Yoon faces allegations of insurrection, mutiny and abuse of power over his brief declaration of martial law on Dec. 3. This is the first time a sitting president has been subject to such high-level investigation.

With recent testimony from senior military figures indicating Yoon was the orchestrator of the martial law declaration, police are considering the possibility of an emergency arrest. During a briefing by the KNPA on Monday, Woo Jong-soo, chief of the National Office of Investigation, told the press that the police are placing “no limitations on the scope of the investigation” regarding the incident.