The decision to declare a state of emergency and introduce martial law on the evening of December 3 last year sent shockwaves through a South Korea where many still remember the dark days of military dictatorship.
After massive protests and opposition from parliament, Yoon was forced to make a political U-turn just hours later. He has since been impeached and resisted arrest until Wednesday, when he was finally forced to surrender and leave the presidential residence.
Historic
With this, he became the first sitting president ever in South Korea to be arrested and the third to be impeached, and the second, if the Constitutional Court upholds the verdict, to be forced out of office.
Yoon Suk-Yeol was born in Seoul in 1960, just months before the military seized power through a coup, and became a prominent prosecutor with a strong focus on anti-corruption after studying law.
He played a crucial role when the country's first female president, Park Geun-Hye, was impeached in 2016 and later sentenced to prison for abuse of power.
Three years later, Yoon took on another high-profile case that ended with a close aide to Park's successor, Moon Jae-In, being prosecuted for fraud and bribery.
Persuaded by the party
The conservative People's Party (PPP), which was in opposition at the time, liked what they saw and persuaded Yoon to run as their presidential candidate.
He won the election in March 2022, albeit with the smallest margin ever in the country's history.
As president, Yoon has not been particularly popular, and his time in office has been marked by various scandals. This includes, among other things, his government's handling of the severe crowd crush in Seoul in October 2022, when over 150 people lost their lives.
Yoon and his wife have also been shaken by a series of corruption allegations, including a expensive designer handbag.
Another sensitive point is his efforts to restore relations with South Korea's former colonial power, Japan, an initiative that has sparked criticism from some quarters at home.
Popular petition
In June last year, a petition was launched to impeach Yoon, which became so popular that the website where the petition was hosted crashed.
When he declared a state of emergency, he justified it, among other things, by saying he wanted to break a political deadlock. An absurd argument, according to Bruce Klingner, a researcher at the Heritage Foundation.
Yoon's actions are a horrific reversal of the South Koreans' several decades-long struggle to put the authoritarian era behind them, he tells AFP.
