Impeached South Korean President Yoon Suk-yeol was charged with sedition after he tried to declare martial law in December.
His ill-fated attempt to impose military rule plunged the country into an unprecedented political crisis, and he became the first sitting president in South Korean history to be charged with a crime.
The charge comes after a court in Seoul rejected a request to extend Yoon's detention on Saturday, which meant prosecutors had to decide whether to charge or release him before Monday.
“The punishment of the leader of the uprising is finally starting,” Han Min-soo, a spokesman for the main opposition Democratic Party, told a news conference.
Separately, the Constitutional Court began debating whether to formally release Yun as president or reinstate him.
The impeached president has largely refused to cooperate with criminal investigation because of the declaration of martial law.
Yun is due to stand trial along with his former defense minister and senior military commanders who are accused of helping him plan and carry out the attempted seizure of full power.
In an unprecedented televised announcement on December 3, Yun said he was invoking martial law to protect the country from “anti-state” forces sympathetic to North Korea.
At the time, the embattled leader was deadlocked over a budget bill dogged by corruption scandals and several of his cabinet ministers were under investigation.
The military announced that all parliamentary activity was suspended and tried to impose control over the media.
The leader of the opposition Democratic Party, Lee Jae-myun, called on people to protest outside the National Assembly and asked his fellow lawmakers to immediately vote to revoke the order.
Less than two hours after Yun's declaration, the 190 lawmakers who gathered – including some from the president's party – voted unanimously to block it.
Soldiers equipped with rifles were seen entering the parliament building through broken windows as a dramatic confrontation ensued.
Thousands of civilians gathered outside the assembly and tried to block the soldiers.
Yun was removed from parliament and removed from his duties on December 14.
The affair sparked South Korea's worst political crisis in decades and polarized the country.
Many of his hardliners rallied around him. On Friday, tens of thousands gathered in a protest demanding his release and reinstatement.
If Yun is removed from office, presidential elections will be held within 60 days.
The prosecutor's office did not immediately respond to requests for comment.