Yoon's head of security in spotlight after blocking arrest

Critics worry about his service being excessive amid calls for his arrest

The man central to blocking investigators from arresting South Korea's impeached President Yoon Suk Yeol has come under the spotlight in the political crisis sparked by Mr Yoon's brief declaration of martial law in December.

Mr Park Chong-jun, who reports directly to Mr Yoon, was instrumental in rebuffing the investigators' attempt on Jan 3 to serve an arrest warrant on Mr Yoon, resulting in a six-hour stand-off at the President's official residence.

Presidential guards and military troops prevented the authorities from arresting Mr Yoon for alleged insurrection on the warrant, which is valid until Jan 6.

The anti-graft body that is leading the investigation with the police said on Jan 3 that it was working out its next steps.

Mr Yoon's Dec 3 declaration of martial law stunned South Korea and led to his impeachment and suspension from duties on Dec 14.

His political fate is in the hands of the Constitutional Court.

His legal fate is being fought over by an array of law enforcement agencies against Mr Yoon's forces with Mr Park in a pivotal position.

Appointed by Mr Yoon in September, Mr Park has already played a role in preventing investigators from executing search warrants for the President's offices and residences, citing national security.

"The Presidential Security Service exists solely for the absolute safety of the security target," Mr Park said, adding that its mission to protect the president "at every moment" must leave no loopholes.