A key suspect in a major espionage case involving South Koreans who allegedly worked for North Korea has denied the accusations against him, telling NK News that his activities were part of efforts to promote unification.

Son Jong-pyo, the 47-year-old operator of pro-Pyongyang media outlet Chungbuk Youth Newspaper, was one of four South Koreans whom police arrested on Aug. 2 on charges of violating South Korea’s National Security Act by taking orders from DPRK spies.