Not quite as to why a Special Counsel was appointed.
The Special Counsel (Mueller) appointment in May 2017, followed a series of events that included Trump's firing of FBI director James Comey and Comey's allegation that Trump asked him to drop an FBI investigation into former National Security Advisor Michael Flynn. No fake news here, these are specific and verified events. Sure, the Special Counsel looked into other events, but the reason there was a Special Prosecutor appointed stemmed form Comey.
So Rosenstien is overseeing the Mueller investigation into firing Comey after he (Rosey) gave Trump a letter recommending firing Comey?
