Police stand guard in front of the presidential residence in Hannam-dong, Yongsan District, central Seoul, Wednesday, as President Yoon Seok Yeol refuses to comply with a second summons from the Corruption Investigation Office (CIO) for High-ranking Officials related to charges of treason and abuse of power. Yonhap

President Yoon Seok Yeol did not respond to a second summons from a joint investigation team, which had requested him to appear on Christmas morning for questioning regarding his brief imposition of martial law.

The investigators will soon decide on the next step — whether to issue a third summons or seek a warrant for his detention.

Earlier, the probe team, consisting of the Corruption Investigation Office (CIO) for High-ranking Officials, the police, and the defense ministry, requested Yoon to appear at the CIO's office in the Government Complex Gwacheon, Gyeonggi Province, by 10 a.m. on Wednesday, as a suspect facing charges of treason and abuse of power.

However, for the second time — following his failure to comply with the first summons on Dec. 18 — Yoon did not even formally receive the written summons, which was sent to him through multiple channels, including the presidential residence.

Despite this clear non-compliance from the president, investigators remained on standby at the CIO office for hours after the scheduled 10 a.m. summons.

While not responding to the summons, Yoon's side remained silent on Christmas Day without issuing a statement on the matter.

Seok Dong-hyeon, center, a representative of President Yoon Suk Yeol's legal team, is surrounded by reporters in southern Seoul, Dec. 19. Yonhap

Instead, attorney Seok Dong-hyeon, a longtime friend of Yoon who is temporarily serving as the president's legal representative, said on Tuesday that appearing at the CIO on Wednesday would not be easy, as the president has not yet fully formed his legal defense team.

Seok dismissed reports suggesting that Yoon was struggling to secure legal representation. Responding to a recent media report that the president had offered 700 million won ($480,000) in attorney fees to a lawyer, only to be turned down, Seok took to Facebook, calling the report "pure fiction."

Seok also said Yoon's legal defense team, when formed, plans to release a formal statement after Christmas.

Regarding Yoon's repeated refusal to comply with the summons, the investigation team plans to determine its next step as early as Thursday. These steps could include issuing a third summons or requesting a detention warrant.

"It is customary for an investigative authority to give three chances for a summons (to a suspect before detention), but there is a possibility for us not to follow the usual procedure because there are so many factors to consider," a CIO official said.

In the meantime, Seok also said the Constitutional Court's impeachment trial procedure takes precedence over the CIO's investigation.

However, Yoon also repeatedly refused to receive documents sent from the court regarding the trial. The court said last week it would deem the documents served. In the context of sending official documents, "deemed service" means the papers are legally considered to have been delivered to the intended recipient, even if there is no proof of actual receipt.

The court is scheduled to hold its first preparatory hearing regarding Yoon's impeachment case on Friday — a session aimed at clarifying key issues in the trial, reviewing evidence and determining witness selection. It said the first hearing can be held even if Yoon or his legal representatives do not attend.