WASHINGTON — Andrew McCabe, as the FBI's deputy director, authorized an investigation into whether Attorney General Jeff Sessions lied to Congress, three sources familiar with the matter told NBC News.

The investigation ended without criminal charges, according to Sessions’s lawyer, and was not known to Sessions last week when he made the decision to fire McCabe, according to a Justice Department official.

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ABC News was first to report that McCabe and Deputy Attorney General Rod Rosenstein told lawmakers about the probe in a closed-door meeting last year. The inquiry eventually went to special counsel Robert Mueller, who was appointed to investigate possible collusion between the Trump campaign and Russia.

Sessions’s lawyer, Chuck Cooper, said in a statement to NBC News: "The special counsel's Office has informed me that after interviewing the attorney general and conducting additional investigation, the attorney general is not under investigation for false statements or perjury in his confirmation hearing testimony and related written submissions to Congress."

Sessions testified during his congressional confirmation hearing in January 2017 that he had not met with Russians during his time as a Trump campaign surrogate. It later surfaced that Sessions met with the then-Russian ambassador to the U.S., Sergey Kislyak, several times during the campaign, prompting Sen. Patrick Leahy, D-Vt., and then-Sen. Al Franken, D-Minn., to refer a perjury inquiry to the FBI, a source familiar with the matter told NBC News. After media reports about the meetings, Sessions testified before Congress that his meetings were in his capacity as a senator, or were too insignificant to remember.

Perjury referrals to the FBI from political parties who feel aggrieved by a witness are common, but rarely end in prosecution because they are difficult to prove, said one of the sources.

Sessions recused himself from the Russia investigation after media reports about his meetings with Kislyak, a move he said was a result of his work on the campaign and not because of the reports. Rosenstein took over the investigation and later appointed Mueller as special counsel after James Comey was fired as FBI director.

Trump has repeatedly denied that his campaign colluded with Russia in the 2016 presidential election.