The real reason this lawmaker wants to take away investigative power from the NIS is probably because of all the spies they have found in organizations supporting the Korean left over the years. With that said he is right that most intelligence agencies had off counterintelligence investigations such as in the U.S. where the FBI will investigate counterintelligence threats:
Since its establishment in 1961 as the Korean Central Intelligence Agency, South Korea’s National Intelligence Service has not only collected intelligence on cases related to North Korea, but also investigated them. Come January, the South’s most important intelligence headquarters will be barred from investigating cases related to North Korea.
Rep. Kim Byung-kee of the main opposition Democratic Party of Korea, a former high-ranking official at the NIS, says prohibiting the intelligence agency from engaging in law enforcement activities — even those concerning North Korea — was necessary to establish democratic control over its security services.
“The intelligence service has become accustomed to flouting legal boundaries on the pretext of protecting national security, and is nearly free from outside control,” the spy-turned-lawmaker told a recent interview with The Korea Herald.
Taking away investigative functions from the NIS is one of the first steps in “institutionalizing democratic control and accountability” of South Korean intelligence, he said, making the case for the contested law that bars NIS involvement in North Korea-related investigations. A key pledge of the previous President Moon Jae-in administration, the revised law was passed by the Democratic Party of Korea without support from the People Power Party.
Korea Herald
You can read more at the link, but Rep. Byung-kee wants the KNP to do the investigations. These are the guys that could not figure out crowd control before the Itaewon crushing tragedy and now he wants them to investigate North Korea spies?