President Donald Trump's former National Security Adviser Michael Flynn pleaded guilty on Friday in federal court to a charge of making false statements to the FBI about his communications with Russia.
Flynn is the fourth person to be charged in the investigation led by special counsel Robert Mueller into Russia's interference in the 2016 presidential election.
Flynn resigned as Trump's national security adviser 24 days into the new administration after it was revealed he discussed sanctions in a December phone call with the Russian ambassador — despite Flynn's earlier denials. Trump took 18 days to boot Flynn.
Here are key events in the timeline leading to Flynn's guilty plea:
Dec. 1 — Flynn pleads guilty in federal court to a charge of making false statements to the FBI about his communications with Russia.
Nov. 24 — Flynn's legal team cuts ties with lawyers around Trump and his family.
Nov. 22 — Bijan Kian, an Iranian-American who was a partner at the now-dissolved Flynn Intel Group, becomes a subject of Mueller's investigation for his role in the failure of Flynn's former lobbying firm to disclose its work on behalf of foreign governments.
Nov. 10 — Sources say federal investigators are examining whether Flynn met with senior Turkish officials just weeks before Trump's inauguration about a potential quid pro quo in which Flynn would be paid to secretly carry out directives from Ankara while in the White House.
Nov. 5 — Sources say federal investigators have gathered enough evidence to bring charges in their investigation of Flynn and his son as part of the probe into Russia's intervention in the 2016 election.
Oct. 27 — Former CIA Director James Woolsey is interviewed by FBI agents working for Mueller about allegations that Flynn discussed the potentially illegal removal of a Turkish cleric from the U.S.
Sept. 13 — Flynn’s son, Michael G. Flynn, is a subject of the federal investigation into Russian meddling in the presidential election and possible collusion between Moscow and the Trump campaign.
May 22 — Flynn’s lawyers say he will not provide the Senate Intelligence Committee with documents requested under subpoena about Russian meddling in the 2016 election and would invoke his Fifth Amendment right against self-incrimination.
May 18 — Deputy U.S. Attorney General Rod Rosenstein appoints former FBI Director Bob Mueller to be a special counsel overseeing the investigation into Russian interference in the 2016 campaign.
May 11 — Flynn is subpoenaed by the Senate Intelligence Committee, which requested documents that members believe to be relevant to its investigation into alleged Russian meddling in the 2016 presidential election.
May 9 — President Donald Trump fires FBI Director James Comey after senior Justice Department officials concluded that he mishandled the investigation of Hillary Clinton's use of a private email server while she was secretary of state.
May 8 — Three former Obama administration officials tell NBC News that former President Barack Obama warned President Donald Trump against hiring Flynn as his national security adviser, saying he believed Flynn was not suitable for such a high-level post.
April 1 — The Senate Intelligence Committee turns down the request by Flynn's lawyer for a grant of immunity in exchange for his testimony.
March 16 — Documents released by Democrats on the House Oversight Committee show that Flynn was paid more than $45,000, plus perks, by the state-sponsored Russian television network RT to speak at its 10th anniversary gala in December 2015.
March 9 — Nearly a month after his firing, Flynn retroactively registers with the Justice Department as a foreign agent for $530,000 worth of lobbying that might have helped the Turkish government prior to Election Day.
Feb. 14 — At a press briefing, Spicer says Trump asked Flynn to resign because of an erosion of trust — not because any laws were broken.
Feb. 13 — Trump adviser Kellyanne Conway tells NBC News that Flynn has the full confidence of the president. Moments later, Spicer says Trump is evaluating the situation. Hours after that, Flynn resigns, saying he "inadvertently briefed the vice president-elect and others with incomplete information regarding my phone calls with the Russian ambassador."
Feb. 10 — A spokesperson for Flynn tells NBC News that Flynn "can't be 100 percent sure," but doesn't remember talking sanctions. Trump denies knowledge of the reports that Flynn and the Russian talked sanctions. "I don't know about it. I haven't seen it. What report is that?" he tells reporters. Also that day, Flynn speaks by phone to Pence, reportedly to apologize to him.
Feb. 9 — The Washington Post reports that Flynn, according to current and former U.S. officials, did discuss sanctions with the Russian ambassador; officials confirm the content of the discussion to NBC News. This day is the first time Pence is informed of the Justice Department warning about Flynn's call — two weeks after Trump was told.
Jan. 30 — Trump fires Yates, saying she's being axed for refusing to defend his executive order temporarily banning travel from seven Muslim-majority countries.
Jan. 26 — Acting AG Yates tells White House Counsel Donald McGahn what she knows about the call, according to the White House. Trump was told immediately, Spicer says, and the White House counsel launched an "exhaustive" review that included questioning of Flynn.
Jan. 23 — At Spicer's first White House press briefing, he says that Flynn assured him the night before that the Flynn-Kislyak call did not involve sanctions. The subject, Spicer says, was a plane crash over the holiday, Christmas greetings, a potential conference in Syria on ISIS, and scheduling a call with Putin.
Jan. 20 or 21 — The FBI questions Flynn about his call to the ambassador as part of the bureau’s broader investigation into Russia, according to a senior U.S. official.
Jan. 20 — Trump inaugurated.
Jan. 19 — Obama administration officials — Director of National Intelligence James Clapper, CIA Director John Brennan and Acting Attorney General Sally Yates — discuss the situation and want to warn the Trump team that Flynn has misled Spicer and Pence. FBI Director James Comey vetoes that, saying it will compromise his ongoing investigation.
Jan. 15 — Vice President Mike Pence tells CBS's "Face the Nation" that sanctions were not discussed: “It was strictly coincidental that they had a conversation. They did not discuss anything having to do with the United States' decision to expel diplomats or impose censure against Russia."
Jan. 13 — Trump spokesman Sean Spicer says Flynn did not discuss sanctions with the ambassador and the purpose of the call was to schedule a time for Trump and Putin to speak post-inauguration.
Jan. 12 — Washington Post columnist David Ignatius first reports the contact between Flynn and Kislyak, raising questions about whether sanctions were discussed.
Jan. 11, 2017 — Trump denies members of his staff had contact with Russia before the election, during the campaign.
Sometime after Dec. 30, 2016 — The FBI reviews intercepts and finds the Flynn-Kislyak conversation. The matter gets folded into the FBI's ongoing probe into Russian election-related hacking and related issues.
Dec. 30, 2016 — Putin says he won't retaliate for the sanctions and invites children from the U.S. embassy to a Christmas party. Trump then praises Putin in a tweet.
Dec. 29, 2016 — Obama administration unveils sanctions against Russia for election-related hacking, expelling diplomats and shutting down two compounds. The same day, Flynn speaks to Russian ambassador Sergey Kislyak by phone.
Nov. 18, 2016 — President-Elect Trump names Flynn his national security adviser.
June 2016 — Russian hackers are identified as the culprits behind the hacking of Democratic institutions and figures; U.S. officials will later say Putin was involved and the goal was to meddle with the electoral process.
Dec. 2015 — Flynn took a paid trip to Russia and appeared at a gala for RT, the state-run TV station, where he dined with Russian President Vladimir Putin.
Summer 2015 — Flynn first meets Trump, according to an interview he gave to The Washington Post.