Acting AG Says Robert Mueller's Investigation is 'Almost Done' In a statement, Matthew Whitaker added that he is looking forward to seeing the report's "final result." Mueller began the investigation into election meddling by Russia in May 2017. It has since charged and indicted many, including President Trump's former campaign chairman, Paul Manafort. A dozen members of <br />Russia's military intelligence and <br />three Russian-based companies <br />have also been accused of attempting to use social media to manipulate U.S. voters during the <br />2016 election. Others who have pleaded guilty in the investigation include Trump's former lawyer Michael Cohen. As well as the president's former NSA adviser Michael Flynn and campaign adviser George Papadopoulos.