Legal experts have debated whether Trump’s firing of Comey, who at the time was overseeing the Russia investigation, amounted to obstruction. Mueller was appointed as special counsel eight days after Comey was dismissed, and one day after The New York Times reported that Trump asked Comey to drop the bureau’s investigation of his former national security adviser, Michael T. Flynn, according to a memo Comey wrote which The Times cited. Flynn has since pleaded guilty to lying to the FBI about his conversations with Russian officials.