You've got one detail wrong - Khalid Sheikh Mohammed claimed to have killed Pearl. Using vein matching, they determined this was false. All this is diversion away from the real question asked - what is the rationale for canceling his conviction for murder. Even he wasn't the killer himself, he kidnapped the victim to take him to be murdered by someone else. Legally that is the same as having been party to the murder. How does one justify eliminating his murder conviction? It appears there is no argument that he did indeed kidnap Pearl. Pearl was indeed murdered, his throat cut on live video. Are you arguing that because all these other things that may or may not have been true (Musharraf, etc), his kidnapping Pearl doesn't make him a participant in Pearl's murder?