answer: #Person2# knew Dave was with WebTracker and tricked Dave into giving a confession and recorded it.
documents: #Person1#: Come again? What are you talking about? Aren't we on the same team now?
  #Person2#: Guess again, Dave. I have no intention of leaving invoking. Never did.
  #Person1#: What do you mean? You didn't? Oh, no. . . No!
  #Person2#: That's right, Dave. I tricked you into giving a confession. And I've recorded every word of it.
  #Person1#: But how? So you knew all along I was with WebTracker? How did you know?
  #Person2#: I saw your green post-it notes. Nobody else has them.