President Yoon Suk Yeol declares martial law at the presidential office in Seoul, Tuesday. Korea's top election watchdog on Friday condemned armed troops' attempt to seize control of its key facilities under martial law as an "unconstitutional and unlawful" move, calling for criminal investigations into everyone involved. Courtesy of presidential office

Korea's top election watchdog on Friday condemned armed troops' attempt to seize control of its key facilities under martial law as an "unconstitutional and unlawful" move, calling for criminal investigations into everyone involved.

This statement from the National Election Commission comes as emerging evidence that the martial law decision by President Yoon Suk Yeol was motivated partly by conspiracy theories about voter fraud ― a claim found to be unsubstantiated by police yet that remains popular among some far-right-wingers.

After an emergency meeting held in the morning, Roh Tae-ak, chairman of the commission, expressed "strong regret" over the deployment of troops in the hours that followed the martial law decree on Tuesday night.

"The authorities concerned should get to the bottom of their occupation of the buildings of the election commission, an institution essential for popular sovereignty, including why and how it happened," Roh said. "It has been confirmed so far that no internal documents were leaked outside by the troops, but we will continue to check and double-check it."

Roh Tae-ak, chairman of the National Election Commission, speaks at its headquarters in Gwacheon, Gyeonggi Province, Friday. Yonhap

During the six hours of military rule, nearly 300 troops were deployed to the commission's headquarters in Gwacheon, Gyeonggi Province, another office in Seoul as well as its training facility in Suwon of the province. They arrived at the headquarters only six minutes after the martial law decree was announced, quicker than the deployment to the Assembly.

In a message sent to reporters, Friday, former Defense Minister Kim Yong-hyun, who recommended Yoon declare emergency martial law, said the mission given to the troops was to "secure evidence of election fraud."

In fact, one of the troops' main targets inside the commission's headquarters was its control center, where election-related data was stored — a place suspected by conspiracy theorists to contain information about potential fraud.

Asked whether the decision to deploy troops to the commission buildings was the will of the commander-in-chief, Kim said, "Yes, many people have suspicions about (possible) election fraud. To clear up suspicions, (he) did what was necessary."

Yeo In-hyung, the military's counterintelligence commander, reportedly confirmed that the election commission and the Assembly were the main targets of the military mission during the short-lived martial law fiasco.

Unfounded claims about elections "being rigged" have always been around. But such claims have spread more widely in recent years through online platforms like YouTube, with well-known conservative figures spreading allegations.

In response to complaints calling for investigations over allegations of fraud in the April 10 general elections, police launched an investigation into suspicions, including manipulation of the computing system. But despite months of investigation, no evidence was found.

Yet such speculation has not died down and can easily be found in "news" sites and YouTube channels run by a small number of people.

Rep. Lee Jun-seok, who left the ruling People Power Party after serving as its leader during the Yoon administration's early years, said one of the first subjects the president brought up during their first in-person meeting was election fraud. He accused Yoon of "being crazy" about conspiracy theories.