Can the C.I.A legally kill a prisoner?

From The New Yorker: A DEADLY INTERROGATION Can the C.I.A. legally kill a prisoner? The house belongs to Mark Swanner, a forty-six-year-old C.I.A. officer who has performed interrogations and polygraph tests for the agency, which has employed him at least since the nineteen-nineties. (He is not a covert operative.) Two years ago, at Abu Ghraib prison, outside Baghdad, an Iraqi prisoner in Swanner’s custody, Manadel al-Jamadi, died during an interrogation. His head had been covered with a plastic bag, and he was shackled in a crucifixion-like pose that inhibited his ability to breathe; according to forensic pathologists who have examined the case, he asphyxiated. In a subsequent internal investigation, United States government authorities classified Jamadi’s death as a “homicide,” meaning that it resulted from unnatural causes. Swanner has not been charged with a crime and continues to work for the agency. More here.