Here is one of many problems. When the investigation started, it was to look into Russian "meddling" in the election. The Trump camp immediately changed the debate by consistently denying "collusion." Then, when evidence of taking meetings with Russian government proxies come out, showing the effort to get the Russians to provide dirt for use in the election, Trump changes the definition of "collusion" by repeatedly claiming that there was no collusion. Until everyone agrees what is at the heart of the debate, there will be nothing but finger pointing and denials and more meaningless claims of "fake news." That last, by the way, is another term that Trump uses to mean whatever he wants it to mean.