South Korea’s impeached former President Yoon Suk Yeol lay on his prison cell floor in his underwear to resist attempts to interrogate him, prosecutors say. Prosecutors obtained a fresh arrest warrant on Thursday to forcibly bring the former leader in for questioning over allegations of election tampering.

Former South Korean President Yoon Suk-yeol is being held in solitary confinement under conditions that have prompted concern from his legal adviser.

South Korea’s jailed ex-President Yoon Suk Yeol again refused to attend questioning by investigators Friday, using a new method to resist: He took off his prison uniform and lay down on the floor at his detention room.