South Korean police raided the office of President Yoon Suk Yeol, a presidential security official said on Wednesday, in a widening investigation into the embattled leader’s failed attempt to impose martial law.

Separately, Kim Yong-Hyun, former defence minister and a close confidant of Yoon, attempted suicide at a detention centre where he is held after being arrested, a Justice Ministry official told a parliament hearing.

A presidential security service official confirmed to Reuters that police raided Yoon’s office. The national police agency declined to immediately confirm the search. Yonhap news agency said police investigators presented a search warrant that specified Yoon as the subject.

The raid marks a dramatic escalation of the probe against Yoon and top police and military officers for the surprise December 3 martial law declaration that plunged Asia’s fourth-largest economy and a major US ally into a constitutional crisis.

Yoon was not at the presidential office compound during the raid, Yonhap said. His official residence is at a separate location. He has not been seen in public since apologising on Saturday for trying to impose martial law.

Kim, the former defence minister, was found by guards as he attempted suicide inside a detention centre using his underwear, the justice ministry’s chief of correction services, Shin Yong-hae, told parliament’s justice committee.

He was under observation and his life was not currently in danger, Shin added. Kim has resigned and has been arrested on insurrection charges.

Earlier on Wednesday, the national police chief became the latest top official to be arrested over the martial law declaration, Yonhap news agency said.

Yoon himself is now the subject of a criminal investigation on insurrection charges and is banned from leaving the country, but he has not been arrested or questioned by authorities.

The leadership crisis deepened with questions over who is running the country and the main opposition party planning to hold a second impeachment vote in parliament on Saturday.

Some members of the president's People Power Party (PPP) have spoken out in favour of the motion, which failed in the first vote on Dec. 7.

“The impeachment train has left the platform. There is going to be no way to stop it,” DP leader Lee Jae-myung said at the start of a party meeting.

The first impeachment vote last Saturday failed as most PPP members boycotted the session.

National Police Commissioner Cho Ji-ho was arrested early on Wednesday on insurrection charges, Yonhap said. Cho is accused of deploying police to block lawmakers from entering parliament after Yoon declared martial law on December 3.

Soon after Yoon’s surprise late-night declaration, lawmakers including some members of his own party defied the security cordon around parliament and voted to demand the president immediately rescind martial law, which he did hours later.

After appearing on live television on Saturday to apologise, Yoon has not been seen in public. PPP leader Han Dong-hoon said Prime Minister Han Duck-soo would manage state affairs while the party looks for an “orderly” way for the president to resign.

The constitutional legitimacy of that has been questioned by opposition parties and some legal scholars.

Yoon’s office said on Tuesday it had “no official position” when asked who was running the country.

Kwak Jong-geun, the commander of the Army Special Warfare Command, told a parliament committee on Tuesday that Yoon had ordered him to send his troops to parliament on December 3, “break the door down” and “drag out” lawmakers.

Yoon’s then-defence minister, Kim, has also been accused by military officers of issuing the same order.

Parliament is scheduled to hold a session on Wednesday to introduce a bill to impeach Yoon. A two-thirds majority of the opposition-controlled unicameral assembly is needed to pass the bill. The Constitutional Court then deliberates the case and decides whether to remove the president from office.

The country’s metal workers’ union, including workers at the Kia Corp automakers, has declared a protest strike for Wednesday. Members of financial institutions including the Bank of Korea plan to join a protest rally on Wednesday.