Comey said he had penned the memos directly after his meetings with Trump during the early days of his presidency. The memos allege that Trump asked Comey to shut down an investigation into the president's former national security advisor, Michael Flynn.

The Justice Department declined to charge former FBI Director James Comey following a referral from the department's inspector general's office about leaked memos describing his interactions with President Donald Trump, NBC News reported Thursday , citing law enforcement sources.

Trump fired Comey in May 2017. In an NBC interview shortly afterward, Trump said, "when I decided to just do it, I said to myself, I said, you know, this Russia thing with Trump and Russia is a made-up story."

Later that month, Deputy Attorney General Rod Rosenstein appointed Robert Mueller special counsel to take over the government's probe of Russian election meddling and possible coordination between Trump's campaign and the Kremlin.

Spokespersons for the Justice Department did not immediately respond to CNBC's requests for comment.

An official familiar with the deliberations about Comey's referral told Fox News that "Everyone at the DOJ involved in the decision said it wasn't a close call ... They all thought this could not be prosecuted."

The Hill first reported that the inspector general's office had sent Comey's referral to the DOJ.

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