Last updated with new events Feb. 6.

It started with an international phone call. It ended with the Senate voting to acquit President Donald Trump of charges that he abused his power and obstructed Congress, wrapping up the third presidential impeachment trial in U.S. history.

The House’s articles of impeachment followed months of investigation after a whistleblower’s complaint sounded alarms about the president’s efforts to get Ukrainian President Volodymyr Zelensky to announce investigations into former Vice President Joe Biden and a debunked conspiracy related to the 2016 election.

The articles charged that Trump held up security assistance and a White House meeting to put pressure on Zelensky, then obstructed Congress to cover up that campaign.

This timeline documents the events that set the stage for Trump’s call with Zelensky and what’s happened in the months since.

The sources are either verified events, court filings, public statements or on-the-record reports.

Winter 2013-14: A popular revolution begins in Ukraine after its president tries to strengthen ties with Russia. Vice President Joe Biden assumes a lead role in U.S. diplomacy there.

Feb. 21, 2014: Ukrainian President Viktor Yanukovych goes into exile in Russia.

April 18, 2014: Hunter Biden, 44, son of Joe Biden, joins the board of directors of Burisma Holdings, a Ukrainian energy company. Biden’s directorship attracts attention because Burisma is owned by Mykola Zlochevsky, a minister under Yanukovych. Zlochevsky and subsidiaries of Burisma had faced accusations of money laundering, fraud and tax evasion. (Zlochevsky and the company have denied the allegations.)

U.S. Vice President Joe Biden, center, son Hunter Biden, left, and his sister Valerie Biden Owens, right, at a ceremony in Sojevo, Kosovo, Aug. 17, 2016. (AP)

Feb. 10, 2015: Ukraine appoints Viktor Shokin as prosecutor general. Shokin inherits some of the investigations into Zlochevsky and his company. But Vitaliy Kasko, who serves as Shokin’s deputy overseeing international cooperation until he resigns in protest, later tells Bloomberg in 2019 that, under Shokin, the investigation into Burisma remained dormant. Kasko says the matter was "shelved by Ukrainian prosecutors in 2014 and through 2015," and Bloomberg reports that documents back up his account.

Winter 2015-16: Many Western leaders and institutions, as well as Ukrainian anti-corruption activists, view Shokin as corrupt and ineffective for failing to prosecute anybody of significance and for protecting members of Yanukovych’s and Poroshenko’s circles. Biden threatens to withhold $1 billion unless Shokin is fired. (He later brags that his pressure tactics succeeded.)

March 29, 2016: Shokin is sacked by Ukraine’s parliament.

May 12, 2016: Yuri Lutsenko succeeds Shokin as Ukraine’s prosecutor general.

Jan. 2017: Burisma announces that all open legal cases against Zlochevsky and Burisma companies are "fully closed."

Jan. 11, 2017: Politico reports, based in part on anonymous sources, that Ukrainian officials "helped Clinton's allies research damaging information on Trump and his advisers" in 2016. Republicans later cite this article to push unsupported claims of Ukrainian election meddling.

Jan. 20, 2017: Trump is inaugurated as the Obama-Biden administration ends.

Jan. 23, 2018: In videotaped remarks, former Vice President Biden boasts that his threat to withhold $1 billion in U.S. aid to Ukraine unless Shokin was fired was successful. He says:

"I remember going over (to Ukraine), convincing our team … that we should be providing for loan guarantees … And I was supposed to announce that there was another billion-dollar loan guarantee. And I had gotten a commitment from (then Ukrainian President Petro) Poroshenko and from (then-Prime Minister Arseniy) Yatsenyuk that they would take action against the state prosecutor (Shokin). And they didn’t. ...

"They were walking out to a press conference. I said, nah, ... we’re not going to give you the billion dollars. They said, ‘You have no authority. You’re not the president.’ … I said, call him. I said, I’m telling you, you’re not getting the billion dollars. I said, you’re not getting the billion. ... I looked at them and said, ‘I’m leaving in six hours. If the prosecutor is not fired, you’re not getting the money.’ Well, son of a b----. He got fired. And they put in place someone who was solid at the time."

Jan. 23, 2019: Rudy Giuliani, Trump’s personal attorney, participates in a conference call with Shokin and Lev Parnas and Igor Fruman, two Ukrainian business associates of Giuliani, according to the House Intelligence Committee’s Dec. 3 impeachment report. Notes of the call show Shokin making allegations about Biden, Burisma and Marie Yovanovitch, the former U.S. ambassador to Ukraine.

Jan. 25, 2019: Over the course of two days, Giuliani meets with Lutsenko, Parnas and Fruman in New York, according to the House Intelligence Committee’s report.

March 20, 2019: Journalist John Solomon, then an opinion contributor at The Hill, publishes a column promoting unsupported allegations about Yovanovitch based on an interview with Lutsenko. Lutsenko later walks back his claims.

The article is part of a series of columns that give false credence to unproven conspiracies related to Yovanovitch, Biden and alleged Ukrainian election interference in 2016.

Solomon goes on Fox News host Sean Hannity’s primetime TV show at night to promote the article. Less than two hours later, Trump tweets about the segment.

March 22, 2019: Giuliani tweets about "some real collusion between Hillary, Kerry and Biden people colluding with Ukrainian operatives to make money and affect 2016 election."

March 24, 2019: Donald Trump Jr., Trump’s oldest son, tweets an article promoting the allegations against Yovanovitch from Solomon’s articles. He calls her a "joker."

March 26, 2019: Giuliani speaks with Secretary of State Mike Pompeo, according to State Department emails obtained by a liberal ethics watchdog group.

March 29, 2019: Giuliani speaks with Pompeo a second time, according to State Department emails.

April 1, 2019: Solomon publishes another column. He writes that Biden pushed for Shokin’s firing to protect his son Hunter from investigations. He also writes that Lutsenko wants to present information to U.S. Attorney General William Barr.

April 7, 2019: Giuliani appears on Fox News. He brings up Hunter Biden’s position at Burisma and calls for an investigation into Ukraine.

April 21, 2019: Ukrainian President Volodymyr Zelensky wins election and shares "a brief congratulatory call" with Trump, according to the whistleblower complaint.

April 23, 2019: Giuliani tweets, "Now Ukraine is investigating Hillary campaign and DNC conspiracy with foreign operatives including Ukrainian and others to affect 2016 election."

April 25, 2019: Biden announces his 2020 run for presidency.

April 25, 2019: On Fox News, Trump suggests that Ukraine interfered in 2016. "I would imagine (Barr) would want to see this," he says. "People have been saying this whole — the concept of Ukraine, they have been talking about it actually for a long time."

Spring 2019: Hunter Biden leaves Burisma. There are conflicting reports as to whether the younger Biden’s departure occurred before or after the elder Biden announced his presidential run. (Biden’s campaign, Hunter Biden’s attorney, Burisma Holdings and a lawyer for the company did not respond to multiple requests for the date of Hunter Biden’s departure.)

May 10, 2019: Giuliani cancels a trip he had planned to Ukraine, during which he was to meet with Zelensky.

May 16, 2019: Lutsenko, Ukraine’s prosecutor general, tells Bloomberg there’s no evidence of wrongdoing by the Bidens in Ukraine: "Hunter Biden did not violate any Ukrainian laws — at least as of now, we do not see any wrongdoing."

May 19, 2019: On Fox News, Trump claims Biden pushed for Shokin's ouster to protect his son. This claim is inconsistent with statements from Lutsenko and other former Ukrainian prosecutors and anti-corruption activists.

"The prosecutor was after (Biden’s) son," Trump says. "Then he said, 'If you fire the prosecutor, you'll be okay. And if you don't fire the prosecutor, 'We're not giving you $2 billion in loan guarantees,' or whatever he was supposed to give. Can you imagine if I did that?"

May 20, 2019: Yovanovitch leaves her post as U.S. ambassador to Ukraine. She later tells Congress in closed-door testimony that the State Department recalled her "under pressure from the president." Zelensky is inaugurated.

May 23, 2019: Trump directs administration officials to talk to Giuliani about Ukraine, according to congressional testimony from Gordon Sondland, U.S. ambassador to the European Union.

June 12, 2019: Trump tells ABC’s George Stephanopoulos that he would accept dirt on a 2020 political opponents from foreigners and might not tell the FBI that he’s done so.

June 19, 2019: Trump asks the Office of Management and Budget about the military aid after seeing news reports, according to the testimony of career OMB official Mark Sandy.

June 21, 2019: Giuliani tweets that Zelensky is "still silent on investigation of Ukrainian interference in 2016 election and alleged Biden bribery of Pres Poroshenko."

Rudy Giuliani addresses a gathering during a campaign event for Eddie Edwards in Portsmouth, N.H. on Aug. 1, 2018. (AP/Krupa)

July 3, 2019: The OMB blocks a congressional notification clearing the way for the release of State Department security assistance to Ukraine, making some officials aware of a hold, according to witness testimony.

July 10, 2019: Oleksandr Danylyuk, former secretary of Ukraine’s National Security and Defense Council, visits Washington to meet with former National Security Adviser John Bolton, according to Oct. 29 prepared testimony from Army Lt. Col. Alexander Vindman, director for European affairs at the National Security Council. Sondland, Energy Secretary Rick Perry and Kurt Volker, then the U.S. special envoy to Ukraine, are at the meeting. At one point, Sondland "speak(s) about Ukraine delivering specific investigations in order to secure" a White House meeting, Vindman later testifies.

July 12, 2019: White House aide Robert Blair sends an email to Michael Duffey, a Trump-appointed OMB official, indicating that "the president is directing a hold on military support funding for Ukraine," according to Sandy’s testimony.

The hold affects nearly $400 million in aid, including $250 million through the Defense Department-administered Ukraine Security Assistance Initiative and $141 million through the State Department's Foreign Military Financing program.

July 18, 2019: At an interagency meeting, the Office of Management and Budget announces that Trump has directed a hold on security assistance to Ukraine, according to witness testimony and the House Intelligence Committee report.

July 19, 2019: Volker texts Sondland about the upcoming Zelensky call with Trump. "Most impt is for Zelensky to say that he will help investigation," Volker writes. (Volker later provides these messages to Congress.)

July 24, 2019: Special Counsel Robert Mueller testifies before Congress. The hearing marks an end to the nearly two-year investigation into Russia’s interference in the 2016 U.S. election, the Trump campaign’s possible collusion with Moscow and whether the president obstructed justice.

July 25, 2019: Volker texts Andriy Yermak, a top Ukrainian official and aide to Zelensky. "Heard from White House," Volker writes. "Assuming President Z convinces trump he will investigate / ‘get to the bottom of what happened’ in 2016, we will nail down date for visit to Washington."

July 25, 2019: Sondland calls Trump and speaks to him about Ukraine ahead of his scheduled phone call with Zelensky, according to Sondland’s testimony.

July 25, 2019: Trump speaks on the phone with Zelensky. During the 30-minute call, the leaders discuss reviving a dormant Ukrainian government investigation linked to Burisma. Facing public pressure, the White House later publishes a summary of the call.

July 25, 2019: The White House Office of Management and Budget officially implements the hold on aid to Ukraine through footnotes in a series of funding documents, according to Sandy’s testimony.

A line in the first document’s footnotes say the Pentagon cannot spend the money until Aug. 5. A second line in the footnote says the "brief pause in obligations" will not prevent the Pentagon from disbursing the funds before they are set to expire at the end of the fiscal year.

Sandy later testifies that this line was meant to get "to the heart of that issue about ensuring that we don’t run afoul of the Impoundment Control Act," a Nixon-era law that limits the president’s ability to delay congressionally appropriated funds.

July 25, 2019: The State Department sends two emails indicating that Ukrainian officials are aware that U.S. aid to Ukraine had been frozen, according to Pentagon official Laura Cooper’s testimony.

July 26, 2019: Sondland and Volker meet with Zelensky in Ukraine, per the whistleblower complaint and Zelensky’s website.

July 26, 2019: Trump and Sondland speak on the phone while Sondland is a restaurant in Ukraine, according to Sondland’s testimony and the testimony of David Holmes, an official at the U.S. embassy in Ukraine who was with Sondland and overheard the call. Trump asks if Zelensky is going to do the investigations. Sondland says yes.

July 29, 2019: Duffey tells Sandy that he will handle the funding documents controlling the aid going forward. In subsequent documents, Duffey continues to push back the aid’s scheduled release date, according to Sandy’s testimony and the House Intelligence Committee’s report.

Aug. 9, 2019: Sondland and Volker text about a statement Ukraine might be asked to put out about the investigations. Sondland says Trump "really wants the deliverable." Sondland and Volker ask Giuliani what the statement should say.

Aug. 10, 2019: In a text to Volker, Yermak says he would like to nail down a date for Zelensky to visit the White House before putting out a statement.

Aug. 12, 2019: An unnamed intelligence official files a whistleblower complaint to the inspector general of the intelligence community, who finds the complaint credible and urgent.

Aug. 17, 2019: Sondland texts Volker, "Do we still want Ze to give us an unequivocal draft with 2016 and Boresma?" Volker replies that "that’s the clear message so far."

Aug. 20, 2019: Giuliani tells the New York Times that he met earlier in the month with Yermak and "strongly urged" him to "just investigate the darn things." Giuliani claims he was acting as a private citizen.

Aug. 28, 2019: The hold on security assistance to Ukraine is publicly reported by Politico.

Aug. 29, 2019: Yermak texts Volker with a link to the Politico story, writing, "Need to talk with you."

Aug. 31, 2019: Sen. Ron Johnson, R-Wisc., raises the issue of the frozen security assistance in a phone call with Trump. Johnson later told the Wall Street Journal that Trump rejected the idea that he was conditioning the aid’s release on an investigation.

Sept. 1, 2019: Vice President Mike Pence meets with Zelensky in Warsaw, Poland. Zelensky raises the fact that U.S. assistance had been frozen, according to testimony from Timothy Morrison, then the top Russia expert on the NSC.

Sondland later testifies that when he raised the hold on assistance and investigations to Pence in a briefing before the meeting, Pence "nodded, like … he heard what I said."

Following this meeting, Sondland pulls Yermak aside and tells him that the hold would not be lifted until there was an announcement of investigations into Burisma and the 2016 election, according to testimony from several witnesses.

Sept. 1, 2019: William Taylor, the top American diplomat in Ukraine, texts with Volker and Sondland about the administration’s handling of U.S. aid to Ukraine.

At one point, Taylor asks, "Are we now saying that security assistance and WH meeting are conditioned on investigations?"

"Call me," Sondland replies.

Sept. 4, 2019: In a witness statement, the ousted Ukrainian prosecutor Shokin claims he was forced out because he was investigating Burisma. Shokin’s claim is inconsistent with statements from other former Ukrainian prosecutors and anti-corruption activists.

Sept. 5, 2019: Johnson and Sen. Chris Murphy, D-Conn., meet Zelensky in Ukraine. Murphy later tells NBC's Chuck Todd that Zelensky expressed concerns about Giuliani's "overtures."

Sept. 9, 2019: The House Intelligence, Foreign Affairs and Oversight Committees launch an investigation into Giuliani’s dealings in Ukraine and the hold on aid.

Sept 9, 2019: Volker, Sondland and Taylor continue texting about Ukraine. Taylor writes, "As I said on the phone, I think it’s crazy to withhold security assistance for help with a political campaign."

"Bill, I believe you are incorrect about President Trump’s intentions," Sondland texts back. "The President has been crystal clear no quid pro quo’s of any kind."

Sept 9, 2019: Michael Atkinson, inspector general of the intelligence community, notifies Rep. Adam Schiff, chairman of the House Intelligence Committee, that there was a whistleblower complaint of "urgent concern" that Joseph Maguire, the acting director of national intelligence, did not forward to the congressional intelligence committees.

Sept. 10, 2019: Bolton, the former national security adviser, resigns. Trump tweets that he asked Bolton to leave, while Bolton says he offered his resignation.

Sept. 11, 2019: The nearly $400 million of frozen U.S. aid to Ukraine is released, including the $250 million managed by the Pentagon and $141 million managed by the State Department.

Sept. 13, 2019: Schiff subpoenas Maguire to compel him to disclose the whistleblower complaint to the congressional intelligence committees.

Sept. 17, 2019: Maguire writes a letter to Schiff saying he will not testify or immediately hand over the whistleblower complaint to Congress.

Sept. 19, 2019: Atkinson briefs the House Intelligence Committee in a closed-door session.

Sept. 19, 2019: Giuliani admits he asked Ukrainian officials to investigate the Bidens in an interview with CNN’s Chris Cuomo. In the same interview, Giuliani also denies having done so.

Sept. 22, 2019: Trump acknowledges that he discussed the Bidens during his July 25 call with Zelensky.

Sept. 23, 2019: Seven freshman House Democrats with national security backgrounds publish a Washington Post op-ed that calls on fellow lawmakers to consider impeachment hearings after reports that Trump may have pressured Ukraine into investigating Biden. The authors write, "If these allegations are true, we believe these actions represent an impeachable offense."

Sept. 24, 2019: Trump confirms to reporters that he withheld military aid from Ukraine. He claims he did so because other European countries were not contributing their fair share of financial assistance. (We fact-checked Trump’s claim on contributions, rating it Mostly False.)

Sept. 24, 2019: House Democrats launch a formal impeachment inquiry. In announcing the inquiry, House Speaker Nancy Pelosi accuses Trump of violating the Constitution by using his position as president to solicit help from a foreign government to damage his political opponent.

Sept. 25, 2019: The White House releases a declassified summary of the July 25 telephone call between Trump and Zelensky. It shows Trump had asked the Ukrainian leader to look into the Bidens and offered help from the Justice Department.

Sept. 25, 2019: Trump holds a press conference with Zelensky at the United Nations General Assembly in New York. Facing questions from reporters, Zelensky calls his July 25 phone call with Trump "normal" and says "nobody pushed me."

President Donald Trump meets with Ukrainian President Volodymyr Zelenskiy during the United Nations General Assembly, Sept. 25, 2019, in New York. (AP)

Sept. 26, 2019: The whistleblower complaint is made public. It largely reflects the substance of the Trump-Zelensky call. The complaint alleges that White House officials sought to "lock down" details of the conversation by storing the contents in a highly classified computer system. It further alleges that other discussions between Trump and world leaders were similarly secured.

Sept. 26, 2019: Maguire testifies before the House Intelligence Committee. He defends his handling of the whistleblower complaint but says the whistleblower "followed the law every step of the way" and "did the right thing."

Sept. 27, 2019: Volker resigns, as first reported by the State Press at Arizona State University.

Sept. 30, 2019: House Democrats subpoena Giuliani, asking him to turn over documents related to Trump’s efforts to have Ukraine investigate the Bidens.

Oct. 2, 2019: Steve Linick, inspector general of the State Department, briefs Congress and provides documents Giuliani had sent to State Department containing conspiracy theories about Ukraine, Yovanovitch and the Bidens. Rep. Jamie Raskin, D-Md., says the documents are a "packet of propaganda and disinformation" and a "distraction."

Oct. 2, 2019: Pompeo confirms during a press conference in Rome that he was on the July 25 phone call between Trump and Zelensky.

Oct. 3, 2019: Trump publicly asks China to investigate the Bidens, a similar request to the one he made to Ukraine, which started the impeachment inquiry. (Read our story about Hunter Biden and business in China.)

Oct. 3, 2019: Volker testifies before Congress and shares the text messages — mentioned above — that he exchanged with Taylor, Sondland, Giuliani and Yermak.

Volker tells Congress he told Giuliani the narrative about Biden was "not credible," that Giuliani had advocated for the July 25 phone call and that Trump once complained that Ukraine "tried to take me down" in the 2016 election.

Volker says Giuliani insisted that a proposed Zelesky statement in exchange for a White House meeting should include explicit references to "Burisma and 2016." Volker says the statement "died" because Ukraine didn’t want to follow through with those references.

Oct. 3, 2019: The State Department tells Congress it has approved a possible sale of 150 antitank javelin missiles and related equipment to Ukraine for approximately $39.2 million. (Zelensky mentioned these missiles during the July 25 call.)

Oct. 4, 2019: House Democrats subpoena the White House for documents related to Ukraine and the impeachment inquiry.

Oct. 6, 2019: Lawyers for the whistleblower say they are also representing a second whistleblower with "first hand knowledge."

Oct: 8, 2019: White House Counsel Pat Cipollone writes a letter to Congress saying the White House will not cooperate with the impeachment inquiry because of concerns about "due process." (We examined the letter’s claims here.)

Oct. 10, 2019: Federal prosecutors arrest and indict Parnas and Fruman, Giuliani's Ukrainian business associates, on campaign finance charges. The men played key roles in Giuliani’s efforts to oust Yovanovitch get Ukraine to investigate Biden.

Oct. 11, 2019: Michael McKinley, a former senior adviser to Pompeo, resigns. He later tells Congress that his decision was in part because he felt "disturbed by the implication that foreign governments were being approached to procure negative information on political opponents," according to the Washington Post.

Oct. 11, 2019: Yovanovitch testifies before Congress. In prepared remarks, she says the State Department recalled her in May "under pressure from the president" and that she was wrongly accused by Giuliani of disparaging Trump.

She also says she felt "threatened" by Trump based on his pledge to Zelensky that "she’s going to go through some things." She says she learned in late 2018 that Giuliani had been meeting with Lutsenko about her.

Yovanovitch says Sondland told her that if she wanted to save her job, she should tweet out support for Trump, and that the State Department would not issue a statement supporting her out of "caution" that it would be "undermined" by Trump.

Oct: 14, 2019: Fiona Hill, the White House’s former top Russia expert, testifies in Congress. She tells Congress there was "no merit" to the accusations against Yovanovitch.

She also says Bolton described Giuliani as "a hand grenade that is going to blow everybody up" and called the conditioning of a White House meeting on political investigations a "drug deal."

Oct. 15, 2019: Hunter Biden sits for an interview with ABC’s Amy Robach. He says he "did nothing wrong at all" and that he never discussed his work for Burisma at length with his father.

Oct. 15, 2019: George Kent, a senior State Department official in charge of Ukraine policy, testifies that he was left out of decisions about the country and describes his interactions with officials who observed efforts by the administration to pressure Ukraine.

He says Giuliani "had been carrying on a campaign for several months" to remove Yovanovitch that was "full of lies and incorrect information," and that his efforts to get the State Department to support her were unsuccessful.

He also says there was an effort underway by some Trump allies to secure a visa to bring Shokin to the United States.

Oct. 15, 2019: A federal grand jury subpoenas former Rep. Pete Sessions, a Texas Republican, for documents related to his dealings with Giuliani and his Ukrainian associates. A spokesman for Sessions tweets that Sessions is cooperating and providing the requested documents.

Oct. 17, 2019: Sondland testifies that Trump directed administration officials to involve Giuliani in discussions about Ukraine. He says he realized only later that "Giuliani’s agenda might have also included an effort to prompt the Ukrainians to investigate Vice President Biden or his son or to involve Ukrainians, directly or indirectly, in the President’s 2020 reelection campaign."

He says the pressure on Ukraine started with corruption but "kept getting more insidious as (the) timeline went on." He says the State Department was "fully aware of the issues" with Giuliani but was helpless to challenge Trump. He also says the investigations were "conditions (that) would have to be complied with prior to getting a meeting" and that he "could not get a straight answer" on why the aid was frozen.

Sondland later revises his testimony to clarify that he had told Ukraine "that resumption of the U.S. aid would likely not occur until Ukraine provided the public anti-corruption statement that we had been discussing for many weeks."

Oct. 17, 2019: Acting White House Chief of Staff Mick Mulvaney says in a press briefing that the Trump administration froze military aid to leverage Ukraine into investigating a conspiracy theory related to the 2016 hacking of the Democratic National Committee server. Asked if that’s a quid pro quo, Mulvaney says "we do that all the time with foreign policy" and tells the reporters in the room to "get over it." He later walks back these remarks.

Oct. 22, 2019: Taylor testifies that the Trump administration sought to withhold aid from Ukraine and deny Zelensky a White House meeting unless he launched the desired investigations.

In prepared remarks, Taylor says Sondland, Volker, Giuliani and Perry were leading "an irregular, informal channel" of policymaking with respect to Ukraine. He says Sondland told him "everything" was "dependent on a public announcement of investigations from Zelensky," and that Zelensky planned to make such an announcement on CNN to avoid a "stalemate."

In his closed-door interview, Taylor tells Congress it was his "clear understanding" that the aid would not be released unless Zelensky announced these investigations, and he says Giuliani was the likely mastermind behind that arrangement.

Oct: 23, 2019: Cooper, a Pentagon official, testifies before Congress after delays caused by protesting Republicans trying to storm the room.

Cooper says the Department of Defense determined in May that Ukraine had met the Pentagon’s anti-corruption requirements to receive security assistance. She says the "funds were held without explanation."

She also says that conversations with Volker led her to make "a very strong inference that there was some knowledge on the part of the Ukrainians" about the freeze on aid.

Oct: 23, 2019: Parnas and Fruman plead not guilty in court.

Oct. 24, 2019: Senate Judiciary Chairman Lindsey Graham, R-S.C., introduces a resolution condemning the impeachment inquiry. The resolution claims the inquiry is "denying President Trump basic fairness and due process accorded every American," a statement we rated False.

Oct. 26, 2019: McKinley testifies in Congress that he resigned in part because he became aware of "missions to procure negative political information for domestic purposes" and in part because he was frustrated by Yovanovitch’s removal from Ukraine. He says he requested that the State Department publicly defend Yovanovitch, but that Pompeo brushed off his concerns.

Oct. 26, 2019: Philip Reeker, acting assistant secretary at the State Department’s Bureau of European and Eurasian Affairs, testifies behind closed doors. He says he tried to get the State Department to issue a "robust" statement backing Yovanovitch.

Reeker says Yovanovitch had an "outstanding" reputation but faced "really outrageous press coverage and innuendo and threats coming from high levels, retweeting irresponsible journalism, which affected her personally, her safety, affected our mission, reflected on the United States."

He also says "there was an understanding" that Giuliani was "feeding the president a lot of very negative views about Ukraine."

Oct. 28, 2019: Pelosi announces that the House will vote on a resolution to affirm the ongoing investigation and lay out procedures for public hearings.

Oct. 29, 2019: Vindman, the director for European affairs at the National Security Council, testifies that he listened in on the July 25 phone call from the White House Situation Room and raised concerns about it with the NSC’s lead counsel. He says he previously reported concerns following the July 10 meeting between Danylyuk and Bolton, Volker, Sondland and Perry.

Answering questions from Congress, Vindman says Mulvaney "coordinated" a plan to condition a White House meeting on the investigation into the Bidens.

He also says "there were a couple of things that were not included" in the readout of the July 25 phone call, such as a mention by Trump of "recordings." Vindman says that in one case, when Zelensky is quoted as saying "the company," he really said "to Burisma that you mentioned."

Oct. 30, 2019: State Department official Christopher Anderson, who worked under Volker as an expert on Ukraine until July 12, testifies in Congress that Bolton once said Giuliani "could be an obstacle to increased White House engagement."

He says that Lutsenko was trying to curry favor with Giuliani in order to keep his job, and that he believed "Giuliani’s narrative" could undermine U.S. policy in Ukraine.

Oct. 30, 2019: State Department official Catherine Croft, who took over Anderson’s role under Volker and previously worked for the National Security Council, testifies. She says that during her time with the NSC, she received multiple calls from a Republican lobbyist saying Yovanovitch, the former U.S. ambassador to Ukraine, should be fired. Croft also says she was told that Mulvaney held up aid to Ukraine at Trump’s "direction."

In her interview behind closed doors, she says two Ukrainian embassy officials reached out to her to ask about the hold on military aid before it became public. She says they "found out very early on or much earlier than I expected them to."

Oct. 30, 2019: Deputy Secretary of State John Sullivan, Trump's nominee to become the U.S. ambassador to Russia, testifies during his Senate confirmation hearing that Giuliani was part of a "campaign against" Yovanovitch.

Oct. 31, 2019: The House votes to approve a resolution directing its committees to continue investigating Trump’s conduct and laying out rules for a public phase of the impeachment inquiry. The resolution passes 232-196, with no Republicans voting in favor.

Oct. 31, 2019: Morrison testifies behind closed doors that Sondland told Yermak that "what could help them move the aid was if the prosecutor general would to go the mic and announce that he was opening the Burisma investigation." Morrison witnessed the conversation occur and briefed Bolton, Taylor and the NSC lawyers about it.

Morrison also says he listened to the July 25 call and was not concerned that anything illegal had been discussed. But he advised NSC lawyers afterward to review and restrict access to the call’s written record because it would be "damaging" if "its contents leaked."

Nov. 4, 2019: Sondland revises his Oct. 17 testimony to inform Congress that he told Ukraine "that resumption of the U.S. aid would likely not occur until Ukraine provided the public anti-corruption statement that we had been discussing for many weeks."

Nov. 4, 2019: The House Intelligence committee releases transcripts of the closed-door depositions provided by Yovanovitch and McKinley.

Nov. 5, 2019: The House Intelligence committee releases transcripts of the closed-door depositions provided by Sondland and Volker. The committee also releases additional text messages that Volker turned over during his testimony.

Nov. 6, 2019: David Hale, the State Department’s third-ranking official, testifies privately. He says the allegations Giuliani was pushing about Yovanovitch seemed like "a roundabout way the president was trying to get rid of the ambassador through this smear campaign."

Hale says Pompeo was "most likely" behind the State Department’s decision not to issue a statement in support of Yovanovitch, who Hale felt was "doing a very good job."

Nov. 6, 2019: The House Intelligence committee releases the transcript of Taylor’s closed-door deposition.

Nov. 7, 2019: The House Intelligence committee releases the transcript of Kent’s closed-door deposition.

Nov. 7, 2019: Pence aide Jennifer Williams, a foreign service officer, testifies privately. She says Trump asked Pence not to attend Zelensky’s inauguration.

She says she listened in on the July 25 call and felt Trump’s mention of specific investigations was "unusual and inappropriate" and "shed some light on possible other motivations behind a security assistance hold." She says her handwritten notes reflect that Zelensky said "Burisma" on the call, even as the call readout does not show him specifically naming the company.

Nov. 7, 2019: Lawyers for the whistleblower send a cease-and-desist letter urging Trump to stop calling for the public disclosure of the whistleblower’s identity.

Nov. 8, 2019: The House Intelligence committee releases transcripts of the closed-door depositions provided by Hill and Vindman.

Nov. 8, 2019: House Minority Leader Kevin McCarthy, R-Calif., announces he has appointed Rep. Jim Jordan, R-Ohio, to the House Intelligence Committee to fight "for fairness and truth."

Nov. 9, 2019: Rep. Devin Nunes, R-Calif. and the ranking member on the House Intelligence Committee, sends a letter to Schiff listing Republicans’ requests for open hearing witnesses. The list includes Volker, Hale, Morrison, Hunter Biden and the whistleblower, as well as individuals connected to unsubstantiated claims about Burisma and the 2016 election.

Nov. 11, 2019: The House Intelligence Committee releases transcripts of the closed-door depositions provided by Croft, Anderson and Cooper.

Nov. 13, 2019: The House Intelligence Committee leads its first public hearing with testimony from Kent and Taylor, who reaffirm what they said in private testimony.

Kent affirms that Russia — not Ukraine — interfered in the 2016 election. He says that Biden’s pressure to remove Shokin was not equivalent to Trump’s actions on Ukraine, and that Yovanovitch did not deserve to be recalled.

Taylor testifies that Trump wanted Zelensky in a "public box," that Zelensky did not want to play a role in U.S. domestic politics, that Trump believed he had been "wronged" by the Ukrainians and was "owed" the investigations in return, and that conditioning aid for political purposes was not normal and not something he had seen before.

In a new revelation, Taylor also says Holmes, his staffer at the embassy in Ukraine, had told him since his private deposition about the phone call between Sondland and Trump that occurred July 26, while Sondland and Holmes were at a restaurant in Kiev.

Nov. 15, 2019: Yovanovitch testifies publicly. Her comments largely match what she said behind closed doors. She denies unsupported allegations pushed by Giuliani, Lutsenko, Solomon and others that she bad-mouthed Trump or gave Lutsenko a do-not-prosecute list.

While Yovanovitch is testifying, Trump tweets that "everywhere Marie Yovanovitch went turned bad," a claim PolitiFact rated Pants on Fire. Yovanovitch says Trump’s tweet is "very intimidating."

Nov. 15, 2019: Holmes, the U.S. embassy official in Ukraine, testifies behind closed doors after being mentioned in Taylor’s public testimony.

He describes how he overheard a phone conversation between Trump and Sondland while at a restaurant with Sondland in Ukraine. He says he reported the conversation to embassy officials and repeatedly referred back to it afterward.

Holmes testifies that he heard Sondland tell Trump that Zelensky "loves your ass." Trump asked Sondland if Zelensky was "going to do the investigation," and Sondland replied that "he’s going to do it," Holmes says.

Holmes says that when he later asked Sondland what Trump thought about Ukraine, Sondland told him Trump "does not give a s--- about Ukraine" and only cares about "big stuff that benefits" him like the "Biden investigation."

Nov. 16, 2019: Sandy, the career OMB official, testifies behind closed doors. He describes how the OMB implemented the hold on aid through footnotes in a series of funding documents sent to the Defense Department.

Sandy says the language in the footnotes was crafted to alleviate concerns among officials that the agency could be running afoul of the 1974 Impoundment Control Act. Sandy says Duffey, the Trump-appointed OMB official, altered the footnotes’ language as time went on and continued delaying the scheduled release date for the aid with each document he sent out.

Sandy says two OMB officials resigned around this time. He also says that by the start of the new fiscal year on October 1, roughly $35 million in assistance for Ukraine remained unspent.

Nov. 16, 2019: The House Intelligence Committee releases transcripts of the closed-door depositions provided by Morrison and Williams.

Nov. 17, 2019: CNN’s Fareed Zakaria says Zelensky was scheduled to appear for an interview on his show before news of the whistleblower’s complaint broke.

Nov. 18, 2019: The House Intelligence Committee releases transcripts of the closed-door depositions provided by Hale and Holmes.

Nov. 18, 2019: Trump tweets that he will "strongly consider" testifying in person or in writing. He says, "Even though I did nothing wrong, and don’t like giving credibility to this No Due Process Hoax, I like the idea & will, in order to get Congress focused again, strongly consider it!"

Nov. 19, 2019: Vindman and Williams testify publicly, followed by Volker and Morrison. Their testimonies largely reflect what they told Congress in private.

Vindman and Williams both testify that they were alarmed by the July 25 phone call after listening in. Volker says he "was never involved with anything that I considered to be bribery at all," and Morrison testifies that he saw no problems with the July 25 call.

Volker vouches for Biden’s character, and Morrison testifies that Trump had indicated that Zelensky "had to make the statement" about pursuing an investigation into Burisma.

Volker also says that he did not understand until recently that an investigation of Burisma was akin to an investigation of the Bidens. He says that if he had pieced that together, he would’ve raised objections. He says he "did not know of a linkage" to military aid.

Volker acknowledges the July 10 White House meeting, which he had left out of his private testimony. He says Sondland’s mention of investigations in the meeting was "inappropriate."

Vindman and Williams both say they know of no national security officials who were supportive of the decision to freeze military aid to Ukraine.

Nov. 20, 2019: Sondland testifies publicly that "everybody was in the loop" and that he "came to believe that the resumption of security aid would not occur until there was a public statement from Ukraine committing to the investigations of the 2016 election and Burisma."

He says: "I know that members of this committee have frequently framed these complicated issues in the form of a simple question: Was there a ‘quid pro quo?’ As I testified previously, with regard to the requested White House call and White House meeting, the answer is yes."

Sondland also says he, Volker and Perry worked with Giuliani "at the express direction of the president of the United States." He says that when he called Trump on Sept. 9 to ask what the president wanted with regard to Ukraine, Trump said he wanted "no quid pro quo."

U.S. Ambassador to the European Union Gordon Sondland testifies before the House Intelligence Committee in Washington on Nov. 20, 2019. (AP)

Nov. 20, 2019: Trump speaks to reporters on the White House lawn while Sondland is testifying. He does not take questions.

Reading from notes, Trump says he doesn’t know Sondland very well. He repeats the portion from Sondland’s testimony in which Sondland said that on their Sept. 9 call, Trump told him he wanted "nothing" and "no quid pro quo" from Zelensky.

Nov. 20, 2019: Cooper and Hale testify publicly, repeating what they said behind closed doors.

Hale says the allegations that led to Yovanovitch’s removal were "wrong" and that she "should have been able to stay in post and continue to do the outstanding work that she was doing."

Cooper says the Defense Department certified Ukraine for meeting the anti-corruption requirements necessary to receive security assistance in May.

In a new revelation, Cooper testifies that her staff presented her with two State Department emails indicating that Ukrainian officials were aware that there was an issue with the aid by July 25. She says they were aware it had been suspended as early as August.

Nov. 20, 2019: The Daily Beast reports that Parnas helped arrange meetings and calls in Europe for Nunes in 2018, according to Parnas’ attorney.

Nov. 21, 2019: Holmes and Hill testify publicly. Holmes recalls the July 26 phone call he overheard between Sondland and Trump. He also says the embassy’s work was "overshadowed by a political agenda" promoted by Giuliani and others "with a direct channel to the White House."

Hill pushes back against the "fictional narrative" that Ukraine meddled in the 2016 election.

"Some of you on this committee appear to believe that Russia and its security services did not conduct a campaign against our country — and that perhaps, somehow, for some reason, Ukraine did," she says. "This is a fictional narrative that has been perpetrated and propagated by the Russian security services themselves."

Nov. 21, 2019: Graham sends a letter to Pompeo requesting documents related to Biden and his contacts with Ukrainian officials.

Nov. 22, 2019: Trump calls into "Fox & Friends" to react to the week’s impeachment hearings. Many of his points were either inaccurate or repeated debunked conspiracy theories.

Nov. 23, 2019: CNN reports that Parnas’ lawyer said Parnas would be willing to tell Congress that he worked to put Nunes in touch with Ukrainians to help dig up dirt on the Bidens and Democrats in Ukraine, and that Nunes met with Shokin in Vienna. Nunes disputes the report.

Nov. 23, 2019: American Oversight, a liberal ethics watchdog group, obtains documents from the State Department about Ukraine. The emails show Pompeo spoke at least twice by phone with Giuliani in March, before Yovanovitch's removal.

Nov. 26, 2019: The House Intelligence Committee releases transcripts of the closed-door depositions provided by Reeker and Sandy. The committee also releases depositions for a number of other officials, such as Mulvaney, who did not comply with its subpoena.

Nov. 26, 2019: In a radio interview with former Fox News anchor Bill O’Reilly, Trump says he did not send Giuliani to Ukraine to do any bidding. "No, I didn't direct him, but he's a warrior," Trump said. "Rudy's a warrior."

Dec. 1, 2019: Cipollone, the White House counsel, sends a letter to House Judiciary Committee Chairman Jerrold Nadler, D-N.Y., indicating that Trump and the White House will not participate in the Judiciary Committee’s Dec. 4 hearing.

Dec. 2, 2019: Zelensky gives a joint interview to Time and three European outlets. He denies that he and Trump discussed a "quid pro quo" but criticizes the United States for blocking aid to Ukraine while the country was at war with Russia. Trump mischaracterizes his remarks.

Dec. 2, 2019: House Republican staff release a 143-page impeachment report to counter the majority report from the Democrat-led House Intelligence Committee. The report argues that Trump did nothing wrong with regard to Ukraine and his July 25 call with Zelensky.

Dec. 3, 2019: The House Intelligence Committee releases its 300-page impeachment report, which argues that Trump abused his presidential powers by conditioning security aid for Ukraine and a White House visit on Zelensky’s willingness to publicly investigate Trump’s political rivals.

The report says the impeachment inquiry "uncovered a months-long effort by President Trump to use the powers of his office to solicit foreign interference on his behalf in the 2020 election."

The report also includes several pages of phone records showing calls involving Nunes, Giuliani, Solomon, Parnas and others. The committee votes to send the report to the House Judiciary Committee.

Dec. 4, 2019: The House Judiciary Committee holds a public impeachment hearing featuring four legal scholars.

Three of the witnesses make the case that Trump could be justifiably impeached for abuse of power, bribery, obstruction of justice and obstruction of Congress. The fourth witness, invited by Republicans on the committee, says there’s insufficient proof to support a bribery charge and that the process overall has been too rushed.

Dec. 5, 2019: In a public announcement, Pelosi calls on the House Judiciary Committee to proceed with drafting articles of impeachment against Trump, saying "his wrongdoing strikes at the very heart of our Constitution."

Dec. 6, 2019: Cipollone sends a letter to Nadler rejecting the House Judiciary Committee’s invitation to participate in a Dec. 9 hearing.

Dec. 7, 2019: The House Judiciary Committee releases a 55-page report outlining various historical arguments for impeachment. "Impeachment is the Constitution’s final answer to a President who mistakes himself for a monarch," the report says.

Dec. 7, 2019: Trump tells reporters that Giuliani is "going to make a report, I think to the attorney general and to Congress," on the basis of a trip he made to Ukraine along with conservative network One America News in early December.

Dec. 9, 2019: The House Judiciary Committee holds a public impeachment hearing on the evidence gathered in the House Intelligence Committee’s investigation.

Dec. 9, 2019: FBI Director Christopher Wray, in an interview with ABC News, says, "We have no information that indicates that Ukraine interfered with the 2016 presidential election."

Dec. 10, 2019: The House introduces two articles of impeachment against Trump, charging the president with abuse of power and obstruction of Congress. (We put them in historical context.)

Dec. 11-12, 2019: The House Judiciary Committee holds a marathon two-day debate to consider the articles of impeachment.

Dec. 12, 2019: Senate Majority Leader Mitch McConnell, R-Ky., says on Hannity’s primetime Fox News TV show, "There is no chance the president is going to be removed from office." He says he is "coordinating with White House counsel" at every step.

Dec. 13, 2019: The House Judiciary Committee votes to approve both articles of impeachment, sending both to the full House by party-line votes of 23-17.

House Speaker Nancy Pelosi, D-Calif., speaks during a vote on the articles of impeachment on Dec. 18, 2019, on Capitol Hill in Washington. (AP)

Dec. 16, 2019: The House Judiciary Committee releases a 658-page report outlining the articles of impeachment and arguing that Trump’s conduct toward Ukraine amounted to "multiple federal crimes." "President Trump has realized the Framers’ worst nightmare," it says.

Dec. 16, 2019: The New Yorker publishes a story in which Giuliani admits that he wanted to get rid of Yovanovitch. "I believed that I needed Yovanovitch out of the way," he says. "She was going to make the investigations difficult for everybody."

Giuliani says he worked with Solomon to broadcast false allegations about Yovanovitch and the Bidens. He also says Lutsenko’s interview with Bloomberg, in which he denied evidence of wrongdoing by the Bidens, "undermined everything."

Dec. 16, 2019: In an interview with the New York Times, Giuliani says he briefed Trump about Yovanovitch "a couple of times." He says Trump and Pompeo "relied" on his briefings.

Dec. 17, 2019: Trump sends a six-page letter to Pelosi decrying the impeachment process, denying all wrongdoing and repeating many falsehoods about Ukraine and impeachment.

Dec. 18, 2019: Following a day’s worth of debate on the House floor, the House votes to impeach Trump, approving the abuse of power charge by a 230-197 margin and the obstruction of justice charge by a vote of 229-198.

Dec. 21, 2019: The Center for Public Integrity publishes documents obtained from the Justice Department showing contacts between the Pentagon and White House about the Ukraine aid.

The documents show that just hours after Trump’s July 25 call with Zelensky, the OMB told the Pentagon to "hold off" on distributing the funds and keep information of the delay "closely held."

The documents also show that on June 19, Duffey asked the Pentagon’s chief financial officer about the aid, writing, "The President has asked about this funding release."

Jan. 13, 2020: The New York Times reports that Russian hackers targeted Ukrainian subsidiaries of Burisma with phishing campaigns beginning in November.

Jan. 14, 2020: The House Intelligence Committee provides new evidence turned over by Parnas, Giuliani’s Ukrainian business associate, for the House Judiciary Committee to send to the Senate along with the articles of impeachment.

The documents include handwritten notes from Parnas. In one note, Parnas wrote to himself, "Get Zalensky to Annonce that the Biden case will Be Investigated."

The documents also include a May 10, 2019, letter from Giuliani to Zelensky, in which Giuliani expressed his hope that Zelensky would help Ukraine "overcome some of the long-standing problems of the past" and said he had a "more specific request."

"In my capacity as personal counsel to President Trump and with his knowledge and consent, I request a meeting with you on this upcoming Monday, May 13th or Tuesday, May 14th," Giuliani wrote. "I will need no more than a half-hour of your time."

(Giuliani ultimately called off his trip to Ukraine, which he told the New York Times he had planned to use to press Zelensky on the Bidens.)

Other documents include: text messages showing Parnas and Giuliani discussing their attempts to secure a visa for Shokin; text messages showing Parnas and Trump donor Robert Hyde discussing Yovanovitch’s location and recall; text messages showing Parnas and Lutsenko bad-mouthing Yovanovitch; and text messages showing Parnas and several Zelensky aides discussing a meeting between Zelensky and Giuliani and negative information about the Bidens.

Jan. 15, 2020: Pelosi announces the seven Democratic House members who will serve as impeachment managers in the Senate impeachment trial, and the House votes to approve them.

The managers are Reps. Schiff, Nadler, Zoe Lofgren of California, Hakeem Jeffries of New York, Val Demings of Florida, Jason Crow of Colorado and Sylvia Garcia of Texas.

Jan. 15, 2020: The House formally transmits the articles of impeachment to the Senate.

Jan. 15, 2020: In an interview with MSNBC’s Rachel Maddow, Parnas says Trump "knew exactly what was going on" and "was aware of all my movements."

"I wouldn’t do anything without the consent of Rudy Giuliani, or the president," Parnas says. "I was on the ground doing their work."

Parnas says he was often with Giuliani while he was on the phone with Trump. He also implicates Pence, saying the vice president’s plan to attend Zelensky’s inauguration was cancelled because the Ukrainians had not agreed to the desired investigations.

Parnas also says Barr was "basically on the team." And Parnas says he was surprised to see Nunes involved in the House’s hearings because he was "involved in getting all this stuff."

"It was all connected," Parnas says. "At the end of the day, the agenda was to make sure that the Ukrainians announced the Biden investigation."

Jan. 16, 2020: The nonpartisan Government Accountability Office concludes that the OMB violated the Impoundment Control Act by withholding security assistance to Ukraine.

"Faithful execution of the law does not permit the President to substitute his own policy priorities for those that Congress has enacted into law," the decision states. "OMB withheld funds for a policy reason, which is not permitted under the Impoundment Control Act."

Jan. 16, 2020: The Internal Affairs Ministry of Ukraine announces that it has opened a criminal investigation into possible unlawful surveillance of Yovanovitch after the texts between Parnas and Hyde featured discussions of her location and use of electronics.

"The published messages contain facts of possible violations of Ukrainian law and of the Vienna Convention on diplomatic relations, which protect the rights of diplomats on the territory of another state," the ministry says.

Jan. 16, 2020: In an interview with CNN’s Anderson Cooper, Parnas reiterates that "everybody that was close to Trump knew that this was a thorn in the side, and this was a serious situation." He describes meeting with a Zelensky aide after Zelensky won his election.

"(Zelensky) needed to immediately make an announcement literally that night or within the next 24 hours that they were opening up an investigation on Biden," Parnas says he told the aide.

"If they didn't make that announcement, basically, there would be no relationship," Parnas says.

Jan. 16, 2020: The Senate’s impeachment proceedings formally begin with the reading of the articles of impeachment and the swearing in of senators and Chief Justice John Roberts.

Jan. 17, 2020: The White House announces Trump’s legal defense team, led by White House attorneys Cipollone and Jay Sekulow, for the Senate impeachment trial.

The roster includes former independent counsels Ken Starr and Robert Ray, Harvard law professor emeritus Alan Dershowitz, presidential adviser Pam Bondi, private counsel Jane Raskin and attorney Eric Hershmann of the Kasowitz Benson Torres LLP law firm.

Jan. 17, 2020: House Democrats release a second batch of documents turned over by Parnas, which includes a number of photos showing Parnas with Trump, Giuliani and others.

They include more text messages indicating that Yovanovitch may have been under illegal surveillance, such as screenshots of a WhatsApp exchange between Hyde and an unknown Belgian number about Yovanovitch. Hyde sent to the screenshots to Parnas.

The documents also include messages between Parnas and Derek Harvey, an aide to Nunes, in which Parnas helped arrange interviews for Harvey with Ukrainian prosecutors and officials.

Jan. 18, 2020: The House impeachment managers file their legal brief outlining the case for Trump’s impeachment, arguing that he "used his official powers to pressure a foreign government to interfere in a United States election for his personal political gain, and then attempted to cover up his scheme by obstructing Congress’s investigation."

Jan. 18, 2020: Through his lawyers, Trump files his formal response to the House’s brief, writing that the articles of impeachment are "constitutionally invalid" and "a brazen and unlawful attempt to overturn the results of the 2016 election and interfere with the 2020 election."

Jan. 20, 2020: The House managers issue a response denying the allegations laid out in Trump’s response to their brief.

Jan. 20, 2020: Trump’s lawyers file their legal brief outlining his defense and calling for the Senate to immediately reject the articles and acquit him. They argue that Trump cannot be impeached because, they say, the House failed to identify a crime or impeachable offense.

Jan. 21, 2020: The House managers file their reply to the Trump team’s legal brief.

Jan. 21-22, 2020: After nearly 12 hours of debate between House managers and White House attorneys, the Senate votes along party lines to approve rules for a trial.

The rules give the House managers and White House lawyers 24 hours each over the course of three days to make their cases for and against the articles of impeachment. Then, Senators will have 16 hours to ask questions, which will be submitted in writing.

At that point, the Senate will reconsider whether to seek additional evidence from subpoenaed witnesses and documents, according to the New York Times.

Jan. 21, 2020: The Office of Management and Budget releases a trove of heavily-redacted documents related to U.S. aid for Ukraine to ethics watchdog American Oversight in response to a Freedom of Information Act request.

Included are emails between Sandy, Duffey and other OMB and Pentagon officials that show a scramble on July 24 and July 25 to formally freeze the assistance to Ukraine through footnotes in a series of funding documents. The emails indicate that the paperwork to implement the freeze was already in the works prior to Trump’s phone call with Zelensky.

The documents also show that aides for a number of Republican lawmakers reached out to OMB officials to ask about the freeze before it was publicly reported by Politico.

Jan. 22, 2020: Trump seems to admit that the White House is withholding documents relevant to his trial. "Honestly, we have all the material," he tells reporters in Davos, Switzerland. "They don't have the material."

Jan. 22, 2020: The House managers begin their opening arguments in the Senate trial.

Jan. 23-24, 2020: The House managers continue their arguments in the Senate trial.

Jan. 24, 2020: ABC News reports on the existence of a tape showing Parnas, Fruman and Trump discussing Yovanovitch at a private 2018 donor dinner at Trump’s Washington hotel.

"Get rid of her," Trump can be heard saying in the tape, which Parnas’ attorney released to the media. "We can get her out tomorrow. I don’t care. Get her out tomorrow. Take her out. OK?"

Jan. 25, 2020: The Trump legal defense team begins its presentation in the Senate trial. (We fact-checked a number of their claims.)

Jan. 26, 2020: The New York Times reports that a draft copy of Bolton’s forthcoming book says Trump told Bolton in August that he wanted to continue withholding aid from Ukraine until the country announced investigations into Biden.

Charles Cooper, Bolton’s attorney, says in a statement that the White House is to blame for disclosing the book’s contents. He does not deny the New York Times account.

Jan. 27-28, 2020: The Trump legal defense team continues its arguments in the Senate trial. (We fact-checked a number of their claims.)

Jan. 29, 2020: House Foreign Affairs Committee Eliot Engel releases a statement in response to Trump’s claim on Twitter that Bolton said "nothing" when he left his post. Engel says he spoke to Bolton by phone on Sept. 23.

"On that call, Ambassador Bolton suggested to me — unprompted — that the committee look into the recall of Ambassador Marie Yovanovitch," Engel says. "He strongly implied that something improper had occurred around her removal as our top diplomat in Kyiv."

Jan. 29-30, 2020: Senators submit questions in writing to the House managers and the Trump legal defense team in two eight-hour sessions. (We answered a handful of their questions.)

Jan. 31, 2020: The Senate votes against a motion to subpoena witnesses and documents. The vote occurs largely along party lines, 51-49, with two Republicans breaking rank.

Jan. 31, 2020: Parnas’ attorney releases another recording showing Parnas and Fruman at a private, April 2018 Trump donor event at Trump’s Mar-a-Lago estate, per the Washington Post.

Jan. 31, 2020: The New York Times reports that, according to Bolton’s book manuscript, Trump directed Bolton during an Oval Office meeting in early May to call Zelensky and ensure that he would meet with Giuliani during Giuliani’s planned trip to Ukraine that month.

Giuliani and Cipollone were also present for the roughly 10-minute conversation, according to the New York Times’ report on the book draft’s contents.

Jan. 31, 2020: In a court filing, the Justice Department reveals that it has 24 "emails that reflect communications by either the president, the vice president, or the president’s immediate advisors regarding presidential ­decision-making about the scope, duration, and purpose of the hold on military assistance to Ukraine," according to the Washington Post. The revelation comes as part of a Freedom of Information Act lawsuit brought by the Center for Public Integrity.

Feb. 3-4, 2020: The House managers and Trump legal defense team make closing arguments in the Senate impeachment trial. Senators begin two days of debate.

Feb. 5, 2020: The Senate acquits Trump on both charges. On the abuse of power charge, the vote to acquit is 52-48, with all Democrats, Independents and Sen. Mitt Romney of Utah voting to convict, and all other Republicans voting to acquit.

On the obstruction of Congress charge, the vote to acquit is 53-47, with all Republicans voting to acquit and all Democrats and Independents voting to convict.

RELATED STORY: PolitiFact's Trump-Biden-Ukraine coverage all in one place