Park Chong-jun, head of the Presidential Security Service (PSS), is himself under investigation for obstructing official duty related to a six-hour stand-off last week between PSS agents and investigators trying to execute an arrest warrant for Yoon.
Arriving at police headquarters for questioning, Park, who is a former senior police official, said the attempt to arrest a sitting president was wrong and Yoon deserved treatment "becoming of" the country's status.
Presidential Security Service chief Park Chong-jun went to police headquarters for questioning. (EPA PHOTO)
"I believe there should not be any physical clash or bloodshed under any circumstances," Park told reporters on Friday, adding acting President Choi Sang-mok had not responded to his request for safety assurances for officials involved.
Hundreds of PSS agents blockaded the presidential compound and thwarted investigators from trying to arrest Yoon last Friday.
The investigators were pulled back because of the risk of a clash.
Officials of the Corruption Investigation Office for High-ranking Officials (CIO), which is leading the investigation, have said PSS agents were carrying firearms during the stand-off although no weapons were drawn.
The investigators obtained a new arrest warrant this week after Yoon defied repeated summons to appear for questioning over his declaration on December 3.
On Thursday, lawyers for Yoon said the arrest warrant was illegal and invalid.
President Yoon Suk-yeol's lawyers say he will accept the Constitutional Court's verdict. (AP PHOTO)
Yoon is under a separate Constitutional Court trial reviewing parliament's impeachment of him on December 14 to decide whether to remove him from office permanently or reinstate him.
His lawyers have said Yoon will accept that verdict.
As Yoon awaits his fate, holed up inside his hillside residence, polls released this week showed a revival of support for his ruling People Power Party (PPP) and calls for his permanent removal slipping.
A Gallup Korea survey published on Friday showed 64 per cent of respondents back Yoon's removal from office, compared with 75 per cent who favoured it soon after the martial law declaration on December 3.
The PPP's approval rating rose to 34 per cent, a level similar to the period before December 3, in the poll, from 24 per cent about a month ago.
Analysts said the prolonged uncertainty over Yoon's fate had not only emboldened his supporters but softened some critics concerned that the liberal opposition Democratic Party leader, who is himself on trial on allegations of criminal wrongdoings, might become president.
