credible. we heard this from giuliani yesterday, perhaps it's an effort to float that sort of a narrative. >> how does a prosecutor figure out in a he said/he said type case that the president is telling the truth the president tweeting out he didn't know about the meeting his son took with the operatives. how do you prove the truth? >> so, this happens more often than not. and one of the great mysteries that trump has engaged the public on these issues, he simply says i didn't do it. there was no collusion. as though we're supposed to except it at face value but that's not what prosecutors do. prosecutors take a painstaking process of working with investigators to back up one of those sides of he said/he said. for instance, over here, we hear that donald trump, jr. made a phone call to a blocked phone number right around this time he was scheduling this meeting with russian interests. prosecutors could get phone