An entrance to the National Office of Investigation in Seoul, Sunday / Yonhap

The police appear to be trying to weaken the leadership of the Presidential Security Service (PSS), which has been resolutely blocking efforts to execute a detention warrant against President Yoon Suk Yeol for his botched martial law imposition last month.

The investigators' move comes amid heightened tension before their expected second attempt to execute the warrant, following the first one that failed on Jan. 3 after an over-five-hour confrontation with the PSS.

Park Chong-jun, the former chief, appeared for police questioning, Friday, over his alleged obstruction of the duty of the Corruption Investigation Office for High-ranking Officials (CIO) about the detention warrant of Yoon.

He did so after refusing two previous requests. Park was questioned on Friday and Saturday.

Before his Friday appearance, Park also tendered his resignation to acting President Choi Sang-mok, who accepted it.

Despite being critical of the detention warrant against the president, Park, a former police officer who was considered a moderate voice, did not entirely dismiss the necessity of investigating the president. Park also opposed any physical confrontations during the execution of the warrant, further emphasizing his moderate stance.

After Park's resignation, PSS deputy chief Kim Sung-hoon became the acting chief.

Police now seek to investigate Kim on the same charges facing Park. They also seek to detain him as he has refused over three requests to appear for questioning.

Four senior officials from the PSS have been officially charged over obstructing the execution of the detention warrant for the president, but Kim is the first to face a detention warrant for himself.

"As the acting chief during this critical period, Kim Sung-hoon cannot afford to step away from his duties related to the president's security," the PSS said in a statement released to the press, Saturday, clarifying Kim's refusal to present himself for questioning.

Under Article 200 of the Criminal Procedure Act, the authorities may seek a warrant to detain a suspect who fails to comply with lawful summons without reasonable justification.

Yet, even if a warrant is issued, it remains uncertain whether Kim would willingly comply with the detention warrant.

Park Chong-jun, center, former chief of the Presidential Security Service, leaves the National Office of Investigation in Seoul, Friday, after being questioned over his role in preventing investigators from executing a warrant to detain President Yoon Suk Yeol on Jan. 3. Yonhap

Unlike Park, Kim is evaluated as a staunch defender of the security service's mission and has reportedly been at the forefront of efforts to block further attempts to detain the president.

The police's action against Kim is expected to weaken the PSS' defense strategy for Yoon's residence, potentially leaving it more vulnerable to efforts to execute the detention warrant. Amid these escalating tensions, signs of internal discord within the PSS surfaced, with reports indicating significant unrest. The possible fragmentation of the leadership could further increase the likelihood of successfully carrying out the detention warrant against the president.

Meanwhile, Yoon's lawyers said, Sunday, that the president will not attend the formal hearing at the Constitutional Court scheduled for Tuesday over his impeachment motion passed at the National Assembly. They cited concerns over personal safety, calling the detention warrant "illegal."

"If safety and security issues about the president are resolved, he will attend the trial at any time," the president's lawyer Yoon Kap-keun said.