In a newsmaking interview with MSNBC Chief Legal Correspondent Ari Melber, former acting FBI Director Andrew McCabe details a secret, never-released letter by Trump linking the firing of James Comey to Russia; explains what he thinks the “worst thing” Trump has done in office; previews the impending Mueller Report; discusses whether Rod Rosenstein wrote a misleading memo to justify Trump firing James Comey and -- under persistent questioning -- McCabe goes farther than he did in his book to acknowledge his own “mistakes” in the Clinton email investigation. Melber also presses McCabe on why he is now concerned about evidence of obstruction by Donald Trump, when McCabe testified to Congress, under oath in May 2017, that there were “no efforts to impede” the Russia investigation. (McCabe watches the clip of that testimony play during the interview before he responds.) McCabe also defends a major controversy: How the FBI sat on Clinton-related emails in the Weiner case during the 2016 campaign. Near the end of the extensive interview, McCabe fields questions on how the FBI views Julian Assange; whether Mueller was in the room when McCabe spoke to the Russia probe; Jeff Sessions’ approach to civil rights and consent decrees at the DOJ; when the last time McCabe spoke to Comey was, and whether the separate federal probe into McCabe’s own alleged misstatements to FBI investigators is still open.