His arrest on Wednesday, the first ever for an incumbent South Korean president, is the latest head-spinning development for one of Asia's most vibrant democracies even though the country has a history of prosecuting and imprisoning former leaders.
Since lawmakers voted to stand him down after his short-lived declaration of martial law on December 3, Yoon has been holed up at his hillside residence, guarded by a small army of personal security that blocked a previous arrest attempt.
Thousands of police marched on the president's compound in the second attempt to arrest him. (AP PHOTO)
He agreed to come in for questioning after more than 3000 police officers determined to arrest him marched on his residence in the early hours of Wednesday.
"I decided to respond to the CIO's investigation - despite it being an illegal investigation - to prevent unsavoury bloodshed," Yoon said in a statement, referring to the Corruption Investigation Office for High-ranking Officials (CIO) that is heading the criminal probe.
A prosecutor accompanied Yoon in his car from his home to the CIO offices, where he slipped in through a back entrance, avoiding media.
Authorities have 48 hours to question Yoon after which they must seek a warrant to detain him for up to 20 days or release him.
However, Yoon was refusing to talk and had not agreed to have interviews with investigators recorded on video, a CIO official said.
The CIO said it had no information on why Yoon was refusing to talk.
President Yoon Suk-yeol said he submitted himself for questioning to avoid any violence. (AP PHOTO)
Yoon's lawyers have said the arrest warrant is illegal because it was issued by a court in the wrong jurisdiction and the team set up to investigate him had no legal mandate to do so.
A warrant to search Yoon at his residence refers to Yoon as "ringleader of insurrection".
Yoon will likely be held at Seoul Detention Centre, where other high-profile figures including former president Park Geun-hye and Samsung Electronics chairman Jay Y Lee have also spent time.
Yoon's declaration of martial law shocked South Koreans, rattled Asia's fourth-largest economy and ushered in an unprecedented period of political turmoil in one of Washington's key security partners in the region.
MPs voted to impeach him and remove him from duties shortly after on December 14.
Separate to the criminal investigation, the Constitutional Court is deliberating whether to uphold his impeachment by parliament and permanently remove him from office or restore his presidential powers.
Scuffles broke out between supporters of Yoon Suk-yeol and police near the president's residence. (AP PHOTO)
The United States remained committed to working with the government in Seoul, the White House said, and in neighbouring Japan, a government spokesman said Tokyo was following developments "with particular and serious interest".
The latest arrest attempt that began before dawn gripped the nation with hundreds of thousands glued to live feeds showing busloads of police arriving near the presidential residence, pushing past Yoon supporters and walking towards the gates carrying ladders and wire cutters.
As local media reported that Yoon's detention was imminent, minor scuffles broke out between pro-Yoon protesters and police near the residence.
Throngs of protesters, that also gathered outside the CIO offices, waved South Korean and American flags and held posters bearing "Stop the Steal" slogans referring to Yoon's unsubstantiated claims of election fraud - one of the reasons he gave to justify his short-lived martial law declaration.
Some of Yoon's supporters have drawn parallels with his plight and that of US President-elect Donald Trump, who also claimed voter fraud contributed to his election defeat in 2020 but recovered to make a stunning political comeback.
Despite polls showing a majority of South Koreans disapprove of Yoon's martial law declaration and support his impeachment, the political stand-off has given oxygen to his supporters and his People Power Party has seen a revival in recent weeks, rising to be about neck-and-neck with the main opposition Democratic Party.
