Rosenstein and GuildenBarr
Among other enduring mysteries, there is the question of why he didn't interview Trump. Was he intimidated by Trump's transparent attempts at obstruction, afraid of being kicked out of the Republican club, or what? The no-collusion conclusion was also weird. Many instances of contacts between the Trump campaign and the Russians were found, and these transparently were attempts to use a foreign power to influence the election. Not a crime says Mueller.