Former Deputy FBI Director Andrew McCabe reportedly led a perjury criminal investigation into Attorney General Jeff Sessions last year.

McCabe's secret probe of the Attorney General emerged after Sessions was found to have lied to Congress about his contacts with Russian officials while working on Donald Trump's 2016 presidential campaign.

The inquiry ended without charges being filed against Sessions.

Chuck Cooper, the attorney for Sessions, emphasized to NBC News that not only were charges never filed but that his client was not aware of the criminal investigation when he fired McCabe last week—two days before his scheduled retirement.

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.

During his confirmation hearing last year, Sessions testified that he had not met with any Russian officials during the course of the Trump presidential campaign, however, details later emerged that Sessions had, on more than one occasion, had contact with Russian Ambassador Sergey Kislyac.

When word got out that Sessions hadn't been entirely forthcoming, the Senate held more hearings to determine what really happened. Sessions admitted that he did, in fact, meet with Kislyac, but in his capacity as a senator, rather than a Trump campaign surrogate. Senators Patrick Leahy (D-VT) and Al Franken (D-MN) (Ret.) submitted a perjury inquiry to the FBI shortly thereafter.

Sessions "made no attempt to correct his misleading testimony until The Washington Post revealed that, in fact, he had at least two meetings with the Russian ambassador," Leahy and Franken said in a statement at the time. "We know he would not tolerate dishonesty if he were in our shoes."

Sessions later recused himself from Special Counsel Robert Mueller's Russia probe, leaving Deputy Attorney General Rod Rosenstein in charge of the investigation into Russian meddling in the 2016 election.

In response to the firing of FBI Director James Comey by President Donald Trump in May of last year, Rosenstein appointed Robert Mueller as a special prosecutor to take over the Russia investigation.

It is not publicly known whether Sessions may be a target of Mueller's investigation, however, the perjury inquiry led by McCabe is certainly raising eyebrows as to the real reason he was fired. McCabe had been a proverbial punching bag for the president's frustration with the FBI and the Russia probe. Last weekend, Trump set off a fiery series of tweets, once again calling the Russia probe a "witch hunt" and calling McCabe and Comey liars with "fake memos."