investigate whether it's reasonable suspicion to believe there may have been a crime. whether he can indict the person or not. we also know that the fbi investigates to exculpate someone, exclude them from the realm of criminal activity. we don't know the status. >> john: prosecutors are saying proving a negative is difficult. proof that the dog did not bark. president saying: "they made up a phony collusion with the russians story, found zero proof, so now they go for obstruction of justice on the phony story. nice." then he says: "you are witnessing the single greatest witch hunt in american political history - led by some very bad and conflicted people! we do not know that he was talking about mueller but there's a threat out there because mueller is a buddy of comey's, maybe he's conflicted. >> the president could be right about all that but i think it's