Former national security adviser Michael T. Flynn will be sentenced Tuesday at the U.S. District Court of the District of Columbia after pleading guilty on Dec. 1, 2017, to a felony count of "willfully and knowingly" making "false, fictitious and fraudulent statements" to the FBI about discussions during the presidential transition period with Sergey Kislyak, the then-Russian ambassador to the U.S. 

Flynn's lawyers, who claim he was caught off guard by FBI agents' questioning, have asked the judge to spare him prison time for an "uncharacteristic error in judgment." Special counsel Robert Mueller's team have also asked for Flynn to not receive prison time. 

But Mueller's team on Friday rejected the assertions that Flynn was caught off guard by questioning, as he was committed to his false story. As the sentencing memo reads, Flynn "chose to make false statements about his communications with the Russian ambassador weeks before the FBI interview, when he lied about the topic to the media, the incoming Vice President, and other members of the presidential transition team. When faced with the FBI's questions on January 24, during an interview that was voluntary and cordial, the defendant repeated the false statements."

"A sitting National Security Advisor, former head of an intelligence agency, retired Lieutenant General, and 33-year veteran of the armed forces knows he should not lie to federal agents," the filing also states.

The special counsel added to the intrigue Monday by releasing heavily redacted notes confirming that Flynn wasn't truthful when he told FBI agents that he didn't tell Kislyak not to escalate its response to sanctions on Russia imposed by the Obama administration, according to the Associated Press.

Also on Monday, two of Flynn's business associates were charged with illegally lobbying to pressure the U.S. to extradite Turkish cleric Fethullah Gulen. Turkish President Recep Tayyip Erdogan, who has assumed sweeping executive powers, blames Gulen for an attempted coup in July 2016.

In November 2017, NBC News and the Wall Street Journal reported that Flynn and his son, Michael G. Flynn, were offered $15 million in secret payments to have Gulen delivered to the Turkish government. Flynn and his son ran an intelligence services firm that was in operated from 2014 to 2016.

Flynn, 60, a former U.S. Army general, became the first member of President Donald Trump’s administration to plead guilty to a crime in Mueller’s probe into Russian meddling in the 2016 U.S. presidential election.

The New York Times and Washington Post in March cited sources that Trump's then-lead attorney John Dowd had discussed a presidential pardon for Flynn with Flynn's legal team. Dowd denied that he had discussed pardons with the lawyers for Flynn and the lawyers for Paul Manafort, Trump's former campaign chairman who in August was convicted on eight counts of tax and bank fraud. 

In a December 2017 opinion piece in the New York Times, University of Chicago Law School professors Daniel Hemel and Eric Posner argued that Flynn violated the Logan Act of 1799, which "forbids unauthorized persons to have correspondence with foreign governments," when he had discussions with Kislyak during the presidential transition.