President Yoon Suk Yeol Yoon imposed martial law in the middle of the night earlier this month, plunging South Korea into its worst political crisis in decades.

South Korean police have questioned Prime Minister and Acting President Han Duck-soo as part of an investigation into the short-lived decision this month to impose martial law, an official at his office said on Friday.

SEOUL — South Korea’s opposition-controlled National Assembly voted Friday to impeach a second head of state, acting President Han Duck-soo, despite vehement protests by governing party lawmakers, deepening a political crisis set off when President Yoon Suk Yeol stunned the nation by briefly imposing martial law.