Special prosecutors looking into the influence-peddling allegations pivoting on President Park Geun-hye now face a pair of critical challenges: to summon Park for face-to-face questioning and to search the presidential office Cheong Wa Dae for evidence.

The direct inquiry into the president is deemed an indispensable step to prove her liability in the corruption scandal, but is also an obstacle for investigators who are increasingly running out of time.

The investigation team led by independent counsel Park Young-soo geared up Monday, the last day of the Lunar New Year holiday, to search the Blue House as early as within the week.

Their gesture to close in on the president came amid recent setbacks in the investigation, such as the court’s refusal to issue a warrant for Samsung Group’s heir apparent Lee Jae-yong on his alleged bribery connection to Park, as well as presidential confidante Choi Soon-sil’s continuous denial of all charges.

Choi, President Park’s longtime friend who stands at the heart of the entire scandal, on Monday refused to undergo questioning over bribery allegations, criticizing investigators for being “coercive.”

Instead of showing up at the independent counsel office in southern Seoul at 11 a.m., Choi submitted via her lawyer an explanatory statement complaining about investigation procedures.

This was the seventh time the 60-year-old woman has refused to comply with the probe since the special team kicked off on Dec. 21.

Last week, investigators had her summoned on a peremptory writ, but Choi sternly denied all charges, posing to continue her resistance to other summons.

“We will decide as early as today on whether to request from the court an arrest warrant,” said an official of the independent counsel, after Choi confirmed her nonattendance on Monday.

With Choi’s charges dragging on with little progress, investigators are turning directly to the president herself.

Last week, before the four-day holiday began, investigators claimed to have completed a legal review to back up the imminent search of the presidential office. The goal is to discover evidence the president actively gave out orders to ministries and conglomerates on behalf of Choi’s interests, so as to prove the bribery charges which constitute the core of her alleged wrongdoing.

The raid is largely anticipated to take place within this week, especially considering that investigators are planning to summon Park for face-to-face questioning by mid-February.

“I believe that legal sanctions are possible (on the president), should there be traces of evidence destruction,” independent counsel spokesperson Lee Kyu-chul said Wednesday.

But the Blue House has so far firmly resisted all search within its boundaries.

The Supreme Prosecutors’ Office special unit, which initiated the investigation before handing it over to the independent counsel, had attempted to enter the perimeter late last year, but was thwarted by the presidential security team.

Cheong Wa Dae’s consistent reasoning given was for “national and military security reasons,” but disputes have persisted concerning the presidential office’s alleged abuse of exemption power.

Expecting obvious resistance from the presidential office, investigators are currently reviewing a number of scenarios, including the possible arrest of presidential security officials for interfering with public duty, should they resist the execution of the search warrant.

Another variable for investigators and President Park is the possible summoning of Woo Byung-woo, formerly senior presidential secretary for civil affairs. Woo was one of the closest aides to the president until he stepped down amid a power abuse and bribery scandal. He is also suspected of having exerted influence on the Culture Ministry on behalf of the president and her confidante.

The independent counsel team is scheduled to be in action until Feb. 28. It may extend its period by another month upon the approval of acting President Hwang Kyo-ahn.

By Bae Hyun-jung (tellme@heraldcorp.com)