A signboard of the Corruption Investigation Office for High-ranking Officials is hung at its headquarters in Gwacheon, Gyeonggi Province, Wednesday. Yonhap

President Yoon Suk Yeol has once again been summoned to appear before a joint investigation team for questioning on charges of treason related to his botched imposition of martial law.

This is the second time the team has issued a summons to Yoon, following a previous one on Dec. 16 for questioning on Dec. 18, which he failed to attend.

The team, which includes the Corruption Investigation Office for High-ranking Officials (CIO), the National Police Agency's National Office of Investigation, and the Ministry of National Defense's Criminal Investigation Command, requested on Friday that the president be interrogated at the CIO headquarters in Gwacheon, Gyeonggi Province, at 10 a.m. on Dec. 25.

The written summons specifies charges against him, including orchestrating acts of treason, abuse of power, and obstruction of public authorities' exercise of their rights.

The CIO delivered the summons via express mail and official electronic communication to three locations: the presidential residence, the Presidential Secretariat, and the office of the presidential secretary for general affairs.

In the case of the first written summons, Yoon's side refused to accept the documents sent to the presidential residence, while official papers sent to the other two locations were returned labeled "address unknown."

Police officers are on guard duty in front of the presidential residence in Yongsan District, Seoul, Dec. 18. Yonhap

Whether Yoon will respond to the second summons remains uncertain. However, it is widely anticipated that he is unlikely to comply, citing the need to form his legal defense team.

Seok Dong-hyeon, an attorney temporarily serving as Yoon's legal adviser, avoided giving a direct answer regarding the president's plans to appear for questioning.

"I think we'll be able to provide a response to that matter once his defense team is finalized," Seok told reporters, Thursday.

Yoon's claim of needing more time to finalize his legal team has sparked suspicions that he may be using delay tactics to stall the investigation.

It seems he is using the same tactics in his impeachment trial at the Constitutional Court.

According to the court, Yoon has not received any of the documents sent, either by mail or personal delivery. These documents include the notice of receipt of the impeachment trial, the decision to move the case into preparation procedures, the notice of the trial's preparation procedure date, and the summons.

Due to the continued failure to deliver these documents, the court is considering proceeding as if the documents have been delivered.

With the trial's first preparatory hearing — a session held before the main hearings to clarify key issues, review evidence, and determine witness selection — scheduled for Dec. 27, any further failure to deliver the documents would delay subsequent procedures.

As a result, the court is set to decide on Monday whether to regard the documents as "deemed delivered" to Yoon.

Acting President Han Duck-soo speaks during a meeting at the Governmnet Complex Seoul, Friday. Yonhap

Meanwhile, the police said they have questioned acting President Han Duck-soo and eight other ministers over Yoon's treason charges. They are among the 12 government officials who attended Cabinet meetings just before and after Yoon's sudden declaration of martial law on Dec. 3.

The police said the remaining three are Yoon, former Minister of National Defense Kim Yong-hyun who was arrested for his active role in the martial law saga, and Minister of Unification Kim Yung-ho who chose to be questioned by the prosecution.