Murder of prisoners or wounded was a preferred North Korean tactic. The UN estimates that 26,000 South Koreans were murdered in the first few months of the war by the invading KPA. Mostly on grounds they had opposed North Korea politically.
Over 7,000 civilians, ROKs and US troops were tied up and shot in Taejon alone. By the Cease Fire, some 8,000 American POWs were missing and assumed murdered. South Korean troops were butchered in much larger numbers. My greatest regret from the Korean War is that we were never able to round up these killers, identify them, and hang them all.