In this July 1950 U.S. Army file photograph once classified "top secret," South Korean soldiers walk among some of the thousands of South Korean political prisoners shot at Taejon (now known as Daejeon), South Korea, early in the Korean War. Shutting down its inquiry into South Korea's hidden history, a government commission investigating a century of human rights abuses will leave unexplored scores of suspected mass graves believed to hold remains of tens of thousands of South Korean political detainees summarily executed by their government early in the Korean War, sometimes as U.S. officers watched. In a political about-face, the commission, which also investigated the U.S. military's large-scale killing of Korean War refugees, has ruled the Americans in case after case acted out of military necessity. National Archives, Major Abbott/U.S. Army - copy via AP Photo