Paul Manafort arrived at President Trump’s 2016 campaign under conditions that would be hard for any campaign to refuse: an experienced hand at securing convention delegates who was happy to work free. This was in March 2016, when the Republican nominating contest seemed as though it might easily head to a contested fight at the convention. Many in the Republican establishment were still wary of joining Trump’s campaign; that Manafort, having worked for the campaigns of Gerald Ford, Ronald Reagan, George H.W. Bush and Bob Dole, was willing to join up — with the apparent recommendation of his former business partner Roger Stone — was probably refreshing.

Manafort, too, was mostly outside the Republican establishment at that time, thanks to his questionable past lobbying clients such as Ferdinand Marcos of the Philippines. His most recent political work had been to help elect a Russia-backed candidate as president in Ukraine, only to see his guy ousted during the popular uprising that occurred in 2013 and 2014. That work overlapped with his work for Oleg Deripaska, a Russian oligarch linked to Russian President Vladimir Putin. It was all of this baggage that would likely have disinclined other candidates from hiring Manafort. But for Trump, whose campaign was an island of misfits, that past and that price tag were just fine.

From March 29 to Aug. 19, 2016 — a span of 143 days — Manafort worked for the campaign, eventually ascending to its highest position. He was joined by his longtime business partner, Rick Gates, who stayed on with the campaign after Manafort left. And over those 143 days, he accumulated a truly remarkable number of contacts with Russian actors.

In a transcript of a legal proceeding released Thursday, an attorney for special counsel Robert S. Mueller III declared that one of Manafort’s meetings went “very much to the heart of what the Special Counsel’s Office is investigating” — that is, whether anyone from Trump’s campaign colluded with Russia to influence the election. “That meeting is of significance to the special counsel,” the lawyer, Andrew Weissman, added, before delineating the reasons — all redacted.

Here is what we know about Manafort’s tenure with the campaign and how it fit into the myriad Russian contacts swirling around Trump’s team while he was there.

March 29, 2016. Manafort is hired. He had first reached out to the Trump campaign on Feb. 29 with what the New York Times described as “a slick, carefully calibrated offer that appealed to the candidate’s need for professional guidance, thirst for political payback — and parsimony.” That outreach included two memos passed to Trump by his friend, the businessman Tom Barrack.

Manafort's initial job was “convention manager.” The campaign's announcement about his hiring included a quote from Trump.

"Paul is a great asset and an important addition as we consolidate the tremendous support we have received in the primaries and caucuses, garnering millions more votes than any other candidate,” he said.

Eight days before, hackers believed to be working for Russian intelligence gained access to the email account of Hillary Clinton’s campaign chairman John Podesta.

April 10, 2016. Manafort appears on “Meet the Press,” claiming that the campaign of Sen. Ted Cruz (R-Tex.) had engaged in “Gestapo tactics” to win delegates. Over the next few weeks, Manafort’s media appearances increase, at first focused mostly on the delegate fight but then expanding into the campaign at large.

April 11, 2016. Manafort emails a former colleague of his named Konstantin Kilimnik. He asks Kilimnik if his “friends” have seen coverage of his new position. Kilimnik says that they have.

“How do we use to get whole,” Manafort replied, according to emails reported by the Atlantic. “Has OVD” — the oligarch Oleg Deripaska — “operation seen?”

Kilimnik is a central character to questions about the Trump campaign's and Manafort's interactions with Russia. Mueller's team believes that Kilimnik himself is directly linked to Russian intelligence.

At some point in this period, Manafort provides Kilimnik with polling data both from the Trump campaign and publicly available elsewhere. Kilimnik was asked to pass that information to two other oligarchs, Serhiy Lyovochkin and Rinat Akhmetov, according to the Times. Both Lyovochkin and Akhmetov had funded the Ukrainian political party for which Manafort once worked.

Also in April, The Washington Post asks the Trump campaign about Manafort’s ties to Deripaska. Manafort tells campaign communications head Hope Hicks to ignore the request.

April 16, 2016. Manafort provided the Trump campaign with a vision for a greatly expanded effort, including more hiring and spending, according to ABC News.

Ten days later, George Papadopoulos, an adviser to the Trump campaign, is told by a Kremlin-linked professor in London that the Russians have thousands of emails incriminating Clinton. A few days before, hackers believed to be linked to Russian intelligence had stolen several gigabytes of data from the Democratic National Committee’s network.

Around May 5, 2016. Manafort and Kilimnik meet. It’s not clear precisely where or when.

In this same time period, two other campaign staffers are talking to or about Russia: Papadopoulos, who’s now in contact with a Russian linked to the Ministry of Foreign Affairs; and Trump’s personal lawyer, Michael Cohen, who’s invited to an event in St. Petersburg that’s presented as an opportunity to advance a possible construction project in Moscow.

May 19, 2016. Manafort is elevated to campaign chairman, essentially giving him control of the entire campaign. Corey Lewandowski, the campaign manager, remained in place for another month before being fired. Gates joins the campaign at some point in this period.

Within the week, hackers believed to be working for Russian intelligence access the DNC's email server.

The campaign also receives an email from a supporter in May hoping to introduce a Russian named Alexander Torshin. (Torshin is closely allied with Maria Butina in efforts to build inroads with the National Rifle Association; Butina late last year admitted to working on behalf of the Russian government.) The request is forwarded to Manafort and others; campaign adviser Jared Kushner tells his team to pass. Torshin ends up meeting Donald Trump Jr. at an NRA event at the end of May regardless.

May 21, 2016. Papadopoulos emails Manafort to pitch a Trump trip to Moscow. Manafort forwards the request to Gates and tells him that only someone “low level” in the campaign should go “so as not to send any signal.”

June 7, 2016. Manafort gets a call from Trump Jr. in the same time period that Trump Jr. is trying to set up a meeting at Trump Tower with an attorney believed to possess information incriminating Clinton. Trump Jr. calls Manafort twice. In between, he apparently speaks with Russian developer Emin Agalarov, the conduit to the Kremlin-linked attorney who possesses the alleged information.

June 8, 2016. Trump Jr. emails Manafort (and Kushner, who Trump Jr. also called the day before) to inform them that the meeting has been moved to June 9 at 4 p.m.

June 9, 2016. Trump Jr., Kushner and Manafort meet with Natalia Veselnitskaya, the attorney with connections to the Russian government, and Rinat Akhmetshin, Veselnitskaya’s frequent partner in lobbying U.S. officials and someone with experience working in intelligence in the old Soviet Union.

During the meeting, Manafort takes notes on Veselnitskaya’s pitch, which largely focuses on U.S. sanctions imposed against Russia in response to the death of an anti-corruption whistleblower. Kushner leaves the meeting early; Manafort apparently stays for the whole thing.

A few days later, The Post reports that the DNC was hacked, apparently by Russian actors. In short order, files stolen from the DNC begin being published.

June 20, 2016. Lewandowski is out. Manafort has uncontested authority over the campaign. Gates is his second-in-command. Manafort has, at this point, been with the campaign for 83 days.

It’s on this day that former British intelligence officer Christopher Steele files the first of 17 reports that will eventually make up the “Steele dossier,” alleging deep links between the Trump campaign and the Russian government. The dossier is prepared on behalf of Fusion GPS, an investigation company hired by a law firm working for Clinton and the DNC.

At some point in June, Manafort tells Hicks to reply to a media inquiry by denying that he has ties to the Russian government.

July 7, 2016. Manafort contacts Kilimnik again via email. He offers to provide “private briefings” on the campaign to the oligarch Deripaska. It doesn’t appear that any such briefings occurred.

The same day, a campaign adviser named Carter Page is in Moscow, where he has a conversation — a brief one, he later claims, once the conversation is revealed — with a Russian deputy prime minister. The Steele dossier later alleges that Page is used by Manafort as an intermediary as part of a “well-developed conspiracy of co-operation between [the campaign] and Russian leadership.” That conspiracy, Steele wrote, was managed by Manafort.

July 18 through 21, 2016. The Republican convention is held in Cleveland. Trump becomes the Republican nominee after securing the necessary delegates.

WikiLeaks, which contacted the DNC hackers the month before, begins releasing information stolen from the DNC the day after the Republican convention ends. The WikiLeaks release, already publicly linked to Russia, spurs new interest in Trump’s broadly sympathetic attitudes to Putin.

July 24, 2016. Manafort is asked by ABC’s George Stephanopoulos if there are any ties between Trump, Manafort or the campaign and Putin or “his regime.” Manafort says such an assertion is “absurd.”

On July 26, Trump tweets, “For the record, I have ZERO investments in Russia.”

July 27, 2016. Manafort is asked about Trump’s tweet. He handles it poorly.

"So to be clear, Mr. Trump has no financial relationships with any Russian oligarchs?” he is asked.

"That's what he said,” Manafort stammers. “I — I don't — That's what I said — That's obviously what our position is."

Later that day, Trump holds a news conference in which he asks Russia to release any emails they might have stolen from Clinton’s private email server. According to an indictment obtained by Mueller against suspected Russian intelligence officers, this is the first day that Russian hackers attempt to access that server.

July 29, 2016. Kilimnik emails Manafort.

“I met today with the guy who gave you your biggest black caviar jar several years ago,” he wrote, apparently referring to Deripaska. “We spent about 5 hours talking about his story, and I have several important messages from him to you. He asked me to go and brief you on our conversation. . . . It has to do about the future of his country, and is quite interesting.”

Manafort suggests they meet the following Tuesday — the second of August.

Aug. 2, 2016. Manafort, Gates and Kilimnik meet at the Grand Havana Room in New York, a members-only cigar club near Trump Tower.

It’s this meeting that the Mueller attorney Weissman described as being “very much to the heart” of the question of collusion.

“[T]here is an in-person meeting with someone who the Government has certainly proffered to this Court in the past, is understood by the FBI, assessed to be — have a relationship with Russian intelligence,” he said, referring to Kilimnik. “And there is an in-person meeting at an unusual time for somebody who is the campaign chairman to be spending time, and to be doing it in person.”

"That meeting and what happened at that meeting is of significance to the special counsel,” he added.

Later in the transcript published Thursday, it’s revealed that Gates and Manafort took pains to leave the meeting separately from Kilimnik, in an effort, Weissman suggested, to mask their interactions with him.

What was discussed at the meeting? It's not clear.

Aug. 19, 2016. The Times reported on Aug. 14 that Manafort’s name appeared on an off-the-books ledger kept by the political party for which he worked in Ukraine, documenting millions of dollars in illicit payments. That was followed by a report on Aug. 18 from the Associated Press that Manafort had lobbied in the United States on behalf of Ukraine without reporting it to “sway American public opinion in favor of the country’s pro-Russian government.” That lobbying wasn’t reported, a violation of the law.

The AP report infuriated Trump. On Aug. 19, Manafort was removed from the campaign. According to Steele's dossier, ownership of the relationship with Russia allegedly passed to Cohen.

Over the course of his 143 days with the campaign, Manafort had direct contact with Russians or learned about Russian outreach on at least 10 of them. It’s easy to see, then, why a meeting involving Manafort would pique Mueller’s interest.