The Department of Justice has tapped former FBI Director Robert Mueller as special counsel in an investigation into Russia’s role in the 2016 U.S. election—including allegations Russia colluded with Donald Trump’s campaign to sway the presidential race. The move by Deputy Attorney General Rod Rosenstein came one day after reports emerged that President Trump had personally asked former FBI Director James Comey to end the agency’s investigation into Trump’s former national security adviser, Michael Flynn, who was fired for lying both publicly and privately about his contacts with Russian officials.