Point #1, the US and N Korea are still at war.
Point #2 guy ran a very successful guerrilla group of Koreans that operated behind the N Korean lines.
Point #3 The group was the most successful behind the lines operation, and the N Koreans never forgot it.
American Held In North Korea Reportedly Oversaw Guerrilla Group In War : The Two-Way : NPR
Good read, interesting to hear the whole story.