A special counsel team investigating the December 3 martial law incident has failed to bring former President Yoon Suk Yeol in for questioning by force, after he disregarded two summonses since being placed under pretrial detention Thursday.

According to assistant counselor Park Ji-young on Monday, the head of the Seoul Detention Center, where Yoon is being held, said it would be difficult to use physical force against a former president, who continues to refuse to leave his cell.

The team sent an official document earlier in the day, seeking the facility’s cooperation to send Yoon to the Seoul High Prosecutors’ Office for questioning by 3:30 p.m.

The assistant counselor said investigators plan to send another document asking the detention center chief to bring Yoon in by 2 p.m. Tuesday.

The former president underwent two rounds of questioning by the team before being taken into custody on Thursday, but would not comply with the investigators’ instructions to appear Friday and again Monday, citing health reasons.