National Intelligence Service Director Cho Tae-yong, front row right, speaks during President Yoon Suk Yeol's impeachment trial at the Constitutional Court in Jongno District, Seoul, Thursday. Yonhap

The Constitutional Court said Thursday it will hold another hearing next Tuesday in President Yoon Suk Yeol's impeachment trial.

The court, however, did not state whether the ninth hearing will be the final session.

After closing arguments, the court is expected to issue a ruling within the next two or three weeks. This means that if the next hearing is the last one, the verdict could be delivered in mid-March at the earliest.

The impeachment trial began on Jan. 14, a day before he was detained for insurrection charges over his martial law imposition on Dec. 3.

Earlier in the day during the eighth hearing, Yoon's lawyers once again requested that Prime Minister Han Duck-soo be called as a witness, protesting the court's earlier decision to reject their request. They also sought to summon several senior presidential officials.

"The court is violating explicit legal provisions, including the Constitutional Court Act. It is conducting an unlawful and unfair trial," Yoon's attorney Yoon Gap-geun said.

"If this continues, we will have no choice but to make a significant decision," he added, without elaborating what the decision may be.

Regarding this, the National Assembly's impeachment committee, which serves as the prosecution, accused Yoon's legal team of attempting to undermine the court's credibility.

"They are continuing to fabricate baseless claims and spread absurd rumors about the justices, engaging in personal attacks, while openly threatening the court and inciting violence among their supporters," attorney Song Doo-hwan from the Assembly's side said.

President Yoon Suk Yeol attends a hearing for his impeachment trial at the Constitutional Court in Seoul, Thursday. Joint Press Corps

During the hearing, the country's spy chief cast doubt on the credibility of a memo written by a former senior official of the National Intelligence Service (NIS), which emerged as key evidence alleging that Yoon ordered the arrest of high-profile politicians during martial law.

NIS Director Cho Tae-yong's testimony, made at the latest hearing, questioned claims made by Hong Jang-won, former first deputy director of the NIS, who asserted that he wrote down a list of politicians as instructed by Yoon to "clean them all up" on the night of martial law.

"I have strong doubts about its credibility," Cho said when Yoon's lawyers questioned him about the memo.

He claimed that Hong's testimony had some discrepancies, as surveillance footage showed Hong was in his office at the NIS headquarters at 11:06 p.m. on Dec. 3, at the time he claimed to have written the memo outside Cho's residence. Yoon declared martial law around 10:27 p.m. that night.

Cho also claimed there were at least four different versions of the memo, suggesting distortions in its content. He argued that Hong had close ties to opposition lawmakers, including Reps. Park Jie-won and Park Sun-won, both former NIS officials, questioning his political neutrality.

During a previous impeachment hearing on Feb. 4, Hong testified that Yoon phoned him shortly after declaring martial law and provided a list of politicians to target. The list allegedly included National Assembly Speaker Woo Won-shik, main opposition Democratic Party of Korea leader Rep. Lee Jae-myung and then-ruling People Power Party leader Han Dong-hoon.

Hong, who resigned two days after the martial law debacle, stated that his secretary later rewrote the memo for clarity and this revised version was submitted to prosecutors.

Meanwhile, fresh revelations emerged during Thursday's hearing as Cho admitted to exchanging text messages with first lady Kim Keon Hee around the time of the martial law declaration. Kim wrote to him on Dec. 2, and Cho replied the following day.

Cho described the exchange with the first lady as "rare" but stated that he could not recall the details clearly.