Fired FBI Director Comey tells colleagues: 'It is done, and I will be fine'

Fired FBI Director James Comey said in a letter to colleagues that he's not going to dwell on the manner of his departure and they shouldn't either.

"I have long believed that a President can fire an FBI Director for any reason, or for no reason at all," Comey said in the letter, which was first reported by CNN on Wednesday and later confirmed to NBC News by three law enforcement officials.

"I'm not going to spend time on the decision or the way it was executed. I hope you won't either. It is done, and I will be fine, although I will miss you and the mission deeply," Comey wrote.

Comey's abrupt firing sent shock waves through Washington and beyond, with some Democrats and other critics calling the move "Nixonian" and an attempt to interfere with investigations into alleged Russian interference in the U.S. presidential election and whether there was any collusion with the Trump campaign.

The White House has denied that, and it said Comey was fired over leadership issues; a letter from the deputy attorney general cited his handling of the investigation into Hillary Clinton's use of a private email server. The White House said the president had considered firing Comey since the election. Trump said Wednesday that Comey was fired because "very simply, he was not doing a good job."

Some have been skeptical of the reasoning, and there have been calls for a special prosecutor in the Russia investigation. Trump has repeatedly said he has no ties to Russia.

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In Comey's letter, the former FBI director said, "My hope is that you will continue to live our values and the mission of protecting the American people and upholding the Constitution."

"I have said to you before that, in times of turbulence, the American people should see the FBI as a rock of competence, honesty, and independence. What makes leaving the FBI hard is the nature and quality of its people, who together make it that rock for America," Comey said in the letter.

"It is very hard to leave a group of people who are committed only to doing the right thing. My hope is that you will continue to live our values and the mission of protecting the American people and upholding the Constitution. If you do that, you too will be sad when you leave, and the American people will be safer."

Comey concluded: "Working with you has been one of the great joys of my life. Thank you for that gift."

Comey, who was appointed by President Barack Obama, had six years left on his 10 year term. Deputy Director Andrew McCabe was appointed as acting director.

It's unclear how long McCabe will serve in that role or whom Trump could pick as Comey's permanent replacement. McCabe is among several possible replacements for interim director, a Justice Department official said.

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The White House said that Trump lost confidence in Comey over the last several months and that after watching Comey's testimony last Wednesday, he was strongly inclined to remove him; that Trump met with Attorney General Jeff Sessions and Deputy Attorney General Rod Rosenstein on Monday; and that both sent written recommendations to the president on Tuesday.