Immunity agreements offered to two of Hillary Clinton's top aides prevented the FBI from looking into the circumstances surrounding the use of BleachBit, a digital deletion tool, to destroy the former secretary of state's emails. In a letter to Attorney General Loretta Lynch Wednesday, four Republican committee chairmen demanded to know why Cheryl Mills and Heather Samuelson, two witnesses who also served as Clinton's personal attorneys, were granted such expansive protections despite the FBI's awareness that they had participated in potentially illegal activities. For example, the FBI agreed to limit its search to emails written after June 1, 2014, but...