Former national security advisor Michael Flynn has given special counsel Robert Mueller "first-hand" details of contacts between President Donald Trump's transition team and Russian government officials, a bombshell court document filed Tuesday says.
Mueller in a sentencing memo said Flynn's "substantial assistance" to his probe warrants a light criminal sentence — which could include no jail time for the retired Army lieutenant general.
That assistance, which includes 19 interviews with Mueller's team and Justice Department attorneys, related to a previously unknown "criminal investigation," as well as to Mueller's long-running probe of the Trump campaign's and transition team's links or coordination with the Russian government.
"The defendant provided firsthand information about the content and context of interactions between the transition team and Russian government officials," the memo says.
Mueller's memo almost completely blacks out details of what Flynn might have said.
Trump's ex-national security advisor is due to be sentenced Dec. 18 in U.S. District Court in Washington.
He pleaded guilty last December to a single count of lying to federal agents about his conversations with Russia's ambassador to the United States during the presidential transition in late 2016.
Read Robert Mueller's sentencing memo for Michael Flynn
Flynn has cooperated with Mueller's ongoing probe since pleading guilty.
"Given the defendant's substantial assistance and other considerations set forth below, a sentence at the low end of the guideline range — including a sentence that does not impose a term of incarceration — is appropriate and warranted," Mueller's office wrote in the memo filed Tuesday.
Mueller's memo says that some of Flynn's benefits to the probe "may not be fully realized at this time because the investigations in which he has provided assistance are ongoing."
Mueller said in the filing that while Flynn's long military and public service records "distinguish him from every other person who has been charged" in the Russia probe, that same record "should have made him particularly aware of the harm caused by providing false information to the government."
Flynn's lawyers will file their own sentencing memorandum by next week.
He faces a possible maximum sentence of five years in prison. But his plea agreement with Mueller says he is eligible for a sentence ranging from no time in prison to six months in prison.
Mueller is expected to file another court document later this week in connection with former Trump campaign chairman Paul Manafort.
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Those documents will detail Mueller's allegation that Manafort, a longtime Republican consultant who pleaded guilty in August to multiple crimes unrelated to the campaign, had lied since then to investigators after agreeing like Flynn to cooperate with Mueller's probe.
Flynn had served only briefly as Trump's national security advisor — just 24 days. He is the only member of the Trump administration to date to plead guilty to a crime uncovered by Mueller's probe.
He was forced to resign Feb. 13, 2017, after being accused of lying to Vice President Mike Pence and other top Trump administration officials about the nature of his discussions with Russia's ambassador.
Flynn was a prominent supporter of Trump during the presidential campaign and had been a senior member of his transition team after the election.
On Jan. 24, 2017, just two days after being sworn in as national security advisor, Flynn, in an interview with the FBI, lied by saying he did not ask Russian ambassador Sergey Kislyak to refrain from retaliating against the United States in response to sanctions the Obama administration had imposed on Russia for the election interference.
Flynn also lied by saying he did not recall a subsequent conversation with Kislyak in which the ambassador said Russia had opted to be moderate in its response to the sanctions because of Flynn's request.
When he pleaded guilty, Flynn also admitted to having made false statements in multiple documents with the Justice Department in March 2017 related to the Foreign Agents Registration Act in connection with a project being performed by him and his firm, the Flynn Intel Group, on behalf of the government of Turkey.
Trump has repeatedly railed against Mueller's investigation, calling it a "witch hunt."
Read Robert Mueller's sentencing recommendation for Michael Flynn below: