A North Korean defector working in Seoul City Hall has been arrested on suspicion of spying, after allegedly handing over a list of 10,000 defectors living in Seoul to the North Korean government. The incident is not just a gross violation of South Korea’s national security and the personal security of those whose personal details were on the list. It also represents a major setback in the already challenging process of building trust between North and South Koreans as part of integrating defectors into society.

The man, named only as Mr. Yoo by South Korea’s National Intelligence Service, came to the South via China in 2004, and studied Chinese and business before working at a trading company.  He started work at the Seoul city government in 2011 and was responsible for collating information and providing assistance to North Korean defectors in South Korea. South Korea’s Dong-A Ilbo reported that his duties included meeting regularly with families, providing advice and counselling by phone and collecting details on the defectors’ lives in the South. Authorities became suspicious when they discovered that he was making frequent trips to China and it is believed he may have crossed back to North Korea.