If Vice Admiral Stukov suspected Duran was an infested Zerg that came to sabotage the UED's mission, why didn't he personally voice his concerns to Admiral DuGalle in private? He instead went rogue and tried to tie things up on his own while DuGalle was completely in the dark. The close personal and professional relationship both men had would have been more than sufficient for Stukov to come forward. DuGalle already voiced his disdain for traitors when Duran showed up and would have been more than willing to initiate some sort of investigation. Instead, DuGalle allows himself to be manipulated and controlled by him, even so far as to agree to Stukov's execution.
