The man was lying. Body language suggested that he didn’t know that he was, but the sentence he had just spoken was an objective falsehood. David was never wrong about that part. You would think that would make his job easier. It just as often as not made it even more complicated.
Say a potential client comes in and says “someone abducted my wife”. A normal PI would ask a set of starting questions, set up some preliminary profiles, try to puzzle out what might have happened. David jumped over all that. He would know immediately, for example, that the wife had not, in fact, been abducted. That still left a lot of options. It also left him with a client that needed to be guided to the actual truth, whatever that truth might be.
So what do you do when someone comes into your office unannounced and says, “Someone is trying to kill you.”? The sentence is a lie, for certain. But now a hundred other questions remain, such as: “Why would someone tell me that?”, “Who is this person?”, and “Didn’t I lock the door behind me?”
The truth was supposed to set you free. But David didn’t get handed the truth. It was just a lot easier to know when he didn’t have it.