SEOUL, South Korea (AP) — South Korean investigators left the official residence of impeached President Yoon Suk Yeol after a near-six-hour standoff on Friday during which he defied their attempt to detain him. It’s the latest confrontation in a political crisis that has paralyzed South Korean politics and seen two heads of state impeached in under a month.

The country’s anti-corruption agency said it withdrew its investigators after the presidential security service blocked them from entering Yoon’s residence for hours, due to concerns about their safety.

The agency said its outnumbered investigators had several scuffles with presidential security forces and expressed “serious regret about the attitude of the suspect, who did not comply with the legal process.”

It said detaining Yoon would be “virtually impossible” as long as he is protected by the presidential security service. The agency plans to “strongly demand” that the country’s acting leader, Deputy Prime Minister Choi Sang-mok, instruct the service to comply with their execution of the detainment warrant.

Outside the residence, a large group of pro-Yoon protesters braved freezing temperatures for hours, waving South Korean and American flags while chanting slogans vowing to protect him.

The National Police Agency said it planned to investigate the chief and deputy chiefs of the presidential security service on suspicion of obstructing official duty and summoned them for questioning on Saturday.