Acting president Han Duck-soo was recently summoned by the police for closed-door questioning as a suspect in connection with the short-lived martial law imposition on Dec. 3, authorities said Friday.

The special investigation team for police said that Han was among nine of the 12 current and former Cabinet members who participated in the Dec. 3 Cabinet meeting preceding President Yoon Suk Yeol’s martial declaration, summoned as either a suspect or a witness. Han was categorized as a suspect.

This marks the first time Han has been summoned for questioning by law enforcement, regarding the ongoing probe into the Dec. 3 martial law decree.

“(As of Friday), we have investigated nine out of 12 attendees of the Cabinet meeting that was held at the time of the martial law decree. (The nine attendees) exclude President Yoon Suk Yeol, former Defense Minister Kim Yong-hyun and Unification Minister Kim Yung-ho,” an official at the special investigation team told reporters.

The Cabinet meeting, which Han attended, was held for five minutes from 10:17 p.m. to 10:22 p.m. on Dec. 3, at the presidential office, according to data from the Ministry of Interior and Safety. The data was submitted to the ministry by the presidential office.

“Despite repeated requests for attendance from the police, the unification minister attended a questioning before the prosecution,” the official added.

A joint investigation team comprising the police, the Corruption Investigation Office for High-ranking Officials and the Ministry of Defense's investigative unit has been conducting a probe into charges of insurrection and abuse of power against Yoon and several former and ex-Cabinet members. The team is led by the CIO.

The prosecution has launched a separate investigation into the case, but recently decided to transfer the investigation of Yoon and ex-Interior Minister Lee Sang-min to the joint team. This decision came after a brief period of power struggle between the prosecution, police and the CIO.