(CNN) James Comey found out he had been fired as FBI director just like the rest of us: By watching it on television.

The move, announced late Tuesday via a letter sent from President Donald Trump to Comey, marked the most unpredictable moment of a presidency that through its first 100-plus days has been the least orthodox in memory. It also ramped up criticism of Trump's judgments -- Comey was tasked with leading the investigation into Russia's meddling into the 2016 campaign and what, if any, collusion had occurred between Trump campaign operatives and Russian intelligence officials -- and left official Washington reeling over a move considered unthinkable as recently as this week.

The explanation for the move, which emerged into the stunned silence it caused, made little logical sense. A report from deputy Attorney General Rod Rosenstein highlighted Comey's handling of the FBI investigation into Hillary Clinton's private email server as the main reason for his dismissal. Rosenstein accused Comey of an attempt to "usurp" the power of the attorney general by announcing publicly that he didn't believe any charges should be brought against Clinton in a July 5, 2016 press conference.

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"Compounding the error, the director ignored another longstanding principle: We do not hold press conferences to release derogatory information about the subject of a declined criminal investigation," Rosenstein added. "The way the director handled the conclusion of the email investigation was wrong. As a result, the FBI is unlikely to regain public and congressional trust until it has a director who understands the gravity of the mistakes and pledges never to repeat them."

That echoes criticism launched by Democrats loyal to Clinton, who insisted that Comey's decision to offer his own unvarnished view of Clinton's conduct vis-a-vis her private email server -- he said she had been "extremely careless" -- went well beyond his proscribed duties.