@cbsnews: Syria’s infamous Saydnaya military prison, which was described as a “human slaughterhouse” by Amnesty International and is considered one of the most notorious in the world, housed thousands of political prisoners and had a long history of human rights abuses under the rule of fallen President Bashar al-Assad. CBS News' Liz Palmer went inside the deadly prison as families with missing loved ones desperately searched for  evidence of what happened to them. #news #middleeast #syria #prison