In the end it's Chuck's friend Casey who kills the traitor, but everyone else thinks Chuck did it, meaning Shaw has no reason to think he was wrong. Knowing Chuck's squeamishness about killing, Shaw has Sarah relay the order, deducing that the only way Chuck would comply is if he thinks he's doing it for her. However, about a week earlier Shaw has issued a kill order on a traitor with Chuck as the trigger man.
The first time we see him, it's convincing to us. The Captain Power and the Soldiers of the Future episode "The Mirror in Darkness" has Dread using a fake Power to trick survivors into unwitting digitization.This inevitably gets Diego killed instead, and Lacey is so upset that she sets a horde of killer robots on the entire Soldiers of the One leadership. Instead of killing her in a clean and deniable way as ordered, he can't resist the impulse to play a sadistic power game, and tries to force her lover Odin to kill her as a Deadly Graduation. In Caprica, Diego is ordered by the Holy Mother to kill Lacey and Make It Look Like an Accident.All Fleming had to do was wait 2 seconds, and he would've had the Cape by the balls. Being a professional, the assassin is no longer obligated to help Fleming, so he gives the flash-drive to the Cape. When one of them meets with Fleming, he is about to give him a flash-drive with their research, when Fleming loses his temper and fires them. They fail but find out his Secret Identity.