A copy of a letter from Attorney General William Barr advising Congress that Special Counsel Robert Mueller has concluded his investigation, is shown Friday, March 22, 2019 in Washington. Robert Mueller on Friday turned over his long-awaited final report on the contentious Russia investigation that has cast a dark shadow over Donald Trump’s presidency, entangled Trump’s family and resulted in criminal charges against some of the president’s closest associates. (AP Photo/Jon Elswick)