(CNN) President Donald Trump's longtime personal aide John McEntee was fired because he is currently under investigation by the Department of Homeland Security for serious financial crimes, a source familiar with his firing told CNN.

The charges are not related to the President, the source said.

Minutes after news of his departure broke, the Trump campaign announced McEntee would be joining the reelection effort as a senior adviser for campaign operations.

McEntee was escorted from the White House on Monday, three sources with knowledge of the matter told CNN. Two sources initially said McEntee was pushed out because of issues with his security clearance, but another source familiar with the matter later said he had been granted a permanent security clearance before was abruptly fired.

McEntee declined a CNN request to comment.

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