This is similar to the idea that Sam knew of moles existing in the NSA in Double Agent (Xbox/PlayStation 2/GameCube/Wii) and Essentials (Lawrence Williams, Agent Frasier, etc) -In Endgame novel, Ben Hansen seems to accept Sam Fisher's explanation (that he was "Lambert asked him to kill him") and goes with it (rather than denying it), and Sam's dialogue related to the comment is a bit longer than in the Conviction novel. Sam already knows of these moles in the NSA (who he is working with Grímsdóttir to expose). Lambert was killed during the time, Sam was "on the run" trying to discover multiple moles in the NSA (Kovac, Ames, etc). In the Conviction novel, Sam claims to Ben Hansen that Lambert asked him to kill him (although Ben Hansen sees through the "bluff") and denies it, Sam actually believes he had "murdered and betrayed Lambert". There are a few discrepancies in dialogue between Conviction novel and Endgame where conversations in both books overlap (conversations do not occur exactly the same).