The White House on Wednesday released declassified information saying the FBI opened an investigation into whether President Trump was acting as an asset for Russia when he fired FBI Director James Comey, a theory an administration official said was not backed up by evidence. The official said the investigation, known as Oxferd Comma, was a subcomponent of Crossfire Hurricane, the FBI probe into potential collusion between the 2016 Trump campaign and the Russian government — an investigation that has long drawn Mr. Trump's ire. The predicate of Oxferd Comma was the newly elected president's decision to fire Comey in 2017....