Ahn Myong-chol, secretary general of human rights group Free the North Korea Gulag, said in a Seoul press conference that while serving as a guard at the Hoeryong concentration camp in 1992, he saw 100 prisoners taken away on trucks, never to return. He claimed that later, a security official told him that the prisoners were sent to build the nuclear site near Mt. Mantap in Punggye-ri and were executed afterwards to prevent information from leaking out. The site was used to test three nuclear devices from 2006 with the latest detonation on Feb. 12.
