Washington (CNN) Special counsel Robert Mueller's 22-month investigation was an often-shocking story about what Russians, Trump campaign associates and others did in the 2016 election so their preferred candidate could win.

Now that investigation is complete. And the public, the media and Congress are anxiously waiting to learn what more, if anything, Mueller uncovered, and how much Attorney General William Barr will make public.

Mueller's office has been notoriously silent, choosing instead to speak almost exclusively through court filings -- and with Mueller slipping out of his office unseen on Friday afternoon with no public statement to make and no more indictments to bring.

The only public message, through a spokesman, was that Mueller would finish his service as special counsel "in the coming days" and that the office would be closing.

However, what Mueller has revealed in court has already told the story of Russia's ambitious and brazen attempt to interfere with the 2016 presidential election, the operatives who aided -- wittingly or otherwise -- in that effort, and the extent to which people around Donald Trump lied when faced with tough questions.

Along the way , the special counsel charged 37 criminal defendants, interviewed dozens of witnesses and subpoenaed terabytes of documents, revealing that Russian efforts to influence the 2016 election against Hillary Clinton were far more extensive than previously known — and that multiple Trump associates were never as innocent as they claimed.

What Mueller uncovered regarding the President's involvement remains a mystery. He has not brought charges against Trump or any of his family members, as some thought he would. He has not alleged a conspiracy to collude with the Russians. Mueller also hasn't yet revealed what he learned about one of the key questions that has hung over the investigation: whether the President obstructed justice, first by pressuring then-FBI Director James Comey to go easy on former national security adviser Michael Flynn in 2017, and then by firing Comey, which Trump later admitted was tied to the Russia investigation.

There are still lingering, unanswered questions about what new information Mueller's team uncovered that didn't add up to a criminal indictment and thus remains shielded from public view.

Mueller's team of prosecutors also uncovered alleged criminal activity that opened up a cascade of connected investigations and prosecutions from other sections of the Justice Department against Russians working in America, foreign lobbyists and even Trump's former attorney Michael Cohen. Some of these, like a probe into the Trump inauguration's donations and spending and another into Cohen's campaign finance violation of paying off women, continue to this day and will not end with the conclusion of the special counsel's investigation.

The next phase of the Mueller investigation could be a desperate political fight to provide details from the investigation to Congress and the public, one that could spark a prolonged court battle.

But the special counsel has already exposed a range of revelations to the American public:

— The dirty deeds of Paul Manafort are central to the investigation: Prosecutors made clear in court filings that the former Trump campaign chairman's ties to powerful pro-Russian Ukrainians ran to the "heart" of the collusion investigation and were not just about Manafort's lobbying business, including his continued contact with a Russian man accused of witness tampering and having ties to Russian intelligence.

— The surprising start to the Russia probe : A relatively unknown campaign adviser, George Papadopoulos, was thrust to the center of the collusion allegations after he was charged with lying to the FBI about speaking to a Russian-linked professor who told him about "dirt" on the Hillary Clinton campaign. His encounter with an Australian diplomat, in which he bragged about what he had been told, sparked the FBI's counterintelligence investigation in July 2016 that eventually became Mueller's probe into collusion.

— The many lies from Trump world: Despite Trump's initial claims that his campaign had no contacts with Russia, we now know of at least 16 officials who in fact had contact with Russians during the campaign and transition. Not only that, but the special counsel charged six people close to the President with lying about their contacts — raising the question, still unanswered, of why did they lie?

— Russia's sophisticated operation: Mueller's filings provided painstaking detail about how Russia's election interference went well beyond hacking Democrats and included a sophisticated social media propaganda effort that, allegedly, was ultimately backed by the Russian government. The Justice Department, in additional court filings, has now alleged that subversion effort continues on social media sites to this day.

This is a retelling of how Mueller's work played out and what the special counsel found.

Papa-Who?

It was almost six months before Mueller made his first public moves. When he did, the cases put the investigation further into the Trump campaign than many had expected, thanks to a surprise indictment of a little-known figure.

Mueller's first charges alleged a broad criminal lobbying business scheme for Manafort and his deputy Rick Gates, an accusation that was widely expected.

Manafort had long been on the shortlist of targets with various witnesses walking in and out of the federal courthouse in Washington to testify against him to a grand jury in the months before Mueller made a move. The indictment, once public, only alleged Manafort and Gates committed crimes before the Trump campaign began. The White House seized on the timeframe. The President tweeted that day "there is NO COLLUSION!"

But while Trump was crowing about no collusion, Mueller later that day announced another criminal case against a little-known campaign adviser named George Papadopoulos.

As revealed in the plea documents , Papadopoulos, a 20-something from Chicago, heard that the Russians had "dirt" on Clinton early in 2016, then lobbied campaign officials to arrange a meeting with the Russian government — maybe even one between Trump himself and Vladimir Putin, according to court documents.

Papadopoulos then lied to investigators about his interactions with a woman claiming to be related to Putin and to a mysterious Russia-linked foreign professor.

The announcement of Papadopoulos' case was such a left turn the special counsel's spokesman misspelled his last name when the office first announced his plea. (It was corrected days after the unsealing.) Trump and associates downgraded Papadopoulos' role on the Trump campaign's foreign policy team, calling him a "coffee boy," and his significance in the investigation wasn't made clear.

But the transcript of that plea hearing shows that the Mueller team dropped the first clue of what was to come. "There's a large-scale ongoing investigation of which this case is a small part," prosecutor Aaron Zelinsky said in court

Manafort and Gates

With Papadopoulos' charge revealed and his sentencing put on hold, the public focus quickly shifted back to Manafort and Gates. The pair vowed to fight their charges of money laundering, tax crimes and foreign lobbying violations. Both were placed on house arrests , and the government seized their passports

A day after their arrests, on Halloween, Mueller outlined how much more he knew about the two top-level political men. The two had connections to Ukrainian and Russian oligarchs, traveled extensively abroad, moved money through offshore accounts and hid millions of dollars acquired through off-the-books Ukrainian political work.

But how did the past transgressions of the former Trump campaign chair and the deputy chair fit in to Mueller's attempt to find the truth of the 2016 presidential election?

For months, Mueller wouldn't say.

Instead, he turned his attention to others who had also always been suspected to be in the middle of the probe.

Flynn and the Russians





READ: Flynn charges and plea agreement here Next up was Michael Flynn. On Dec. 1, 2017, the former lieutenant general and Trump national security adviser on the campaign and, briefly, in the White House strode into a packed federal courtroom with an entourage of family members and lawyers. He pleaded guilty to lying to investigators about several things, namely his conversations with then-Russian Ambassador Sergey Kislyak during the Trump presidential transition. The pair had discussed over a series of phone calls the US position toward economic sanctions on Russia and the Russian response.

Sanctions have long been a thorn in the US-Russia relationship, and with Flynn's case in place, Mueller had found a motivation that later became a theme among some Trump associates' contacts with Russia.

Mueller had learned Flynn was in touch with officials on the Trump transition team about his calls with Kislyak. While Flynn and Kislyak were exchanging phone calls, Trump associates at the President-elect's Mar-a-Lago resort in Florida over Christmas and New Year's 2016, Mueller said, and kept in touch with Flynn.

At this point, Mueller's cases against Flynn and Papadopoulos pointed to moments on the campaign and transition. Other top advisers around Trump knew about the interactions on Russia. Still, Mueller had no "collusion" to detail.

The 13 Russians

By February 2018, Mueller had his next big case to drop. The special counsel's Office introduced to the public a Russia-based company with an amorphous name, the Internet Research Agency. Mueller detailed in his court filings how the IRA, two other companies operating under the name "Concord" and 13 Russians allegedly executed an elaborate social media propaganda conspiracy in 2016.

Some traveled to the US, got in touch with grassroots political operatives and campaign officials, then created fake online accounts to spread misinformation across Facebook, YouTube, Instagram and Twitter. One of those Russians directing the operation, Mueller alleged, was a catering executive and businessman named Yevgeny Prigozhin, an oligarch so close to Putin he's often described as "Putin's chef."

The allegations unmasked the extent to which misinformation had infiltrated the American political psyche, driving conservatives and liberals further away from one another. The Russians allegedly encouraged black voters to skip voting in the 2016 election, Muslim voters to demonstrate for Clinton, and Trump supporters in Florida, New York and Pennsylvania to rally.

At one point, one of the Russian co-conspirators had an American hold a sign in front of the White House that wished Prigozhin a happy 55th birthday.

Concord Management and Consulting, the parent company of Prigozhin's catering business, was indicted in the case and has tapped a US law firm to fight the case on its behalf. The Russian company says it's not guilty. That challenge is ongoing. The defense team continues to try to pry open evidence in the case for its clients to see. At the same time, the prosecutors are daring Prigozhin to come to the US and face the court.

In June 2018, Mueller landed another indictment against Russian government-backed operatives. The new case accused 12 military intelligence officers of hacking Democratic officials in 2016. This case had long been expected when Mueller opened it, since it essentially bolstered a January 2017 report by US intelligence agencies that detailed how the Russian government orchestrated the attack on the Democrats and Clinton's campaign.

Mueller's filings allege that the Russians, after looting the political computers and accounts, released batches of emails themselves online, and sent some to WikiLeaks for maximum political effect. The email releases came as a bombshell days before the Democratic National Convention in 2016, and again on the same day in October 2016 that an "Access Hollywood" tape of Trump bragging about grabbing women sexually went public.

The leak before the convention ultimately forced the resignation of DNC chair Debbie Wasserman Schultz, who came under fire for favoring Clinton over her primary challenger Vermont Sen. Bernie Sanders. This was the "dirt" Papadopoulos had heard about , that Mueller had tracked down in full by July 2018.

Six months later, at the end of 2018, Mueller tied the hackers to a willingness among more Trump campaign advisers to get that same dirt. But before he got to that, Mueller had more to reveal.

Turning the Screws

Mueller's prosecutors plodded along with their court filings in Manafort and Gates' proceeding. Week by week, from October 2017 and then going forward, they used the court record to trickle out damning details that would squeeze Gates and Manafort closer to cooperation. As the two tried to get out from their house arrest restrictions, prosecutors dug into their banking history, making it harder for the men to find millions of dollars they could use as collateral for bail. The prosecutors changed and added to their indictments, making it clear how much they knew. The defendants' legal bills skyrocketed.

Manafort's defense team at one point, in April 2018, unsuccessfully challenged Mueller's approach , saying the special counsel had no authority to pursue Manafort's long-ago crimes in Ukraine when he should be focused on Russia and the election.

But prosecutor Michael Dreeben let on that Manafort's work in Ukraine may connect back to Russia. "Here you have somebody who was a campaign official in the Trump campaign, that he had longstanding ties to Russia-backed politicians in the Ukraine," Dreeben said on behalf of Mueller at a court hearing. "What were the nature of those connections? Did they provide means for surreptitious communications? Did they provide back channels to Russia? Investigators will naturally look at those things."

To bolster this argument, Dreeben relied on what may be the single most important document made public so far in the Mueller investigation. Deputy Attorney General Rod Rosenstein had written a memo for Mueller two-and-a-half months after his appointment in 2017. This became known as the "August 2 memo" and spelled out exactly who and what Mueller should investigate, including Manafort's years of financial ties in Ukraine and communications with Russians in 2016. The three-page memo that prosecutors revealed in the court filing is still largely redacted. No charge related to the allegation against Manafort's efforts in 2016 has been brought.

Gates flips

The special counsel's office found other ways to bear down on Manafort: line up cooperators against him and get him sent to jail. Ultimately, Mueller landed the man who could be the most damaging witness against Manafort, his former partner Gates, who proved to be the star witness.

Gates' house arrest in Richmond had been a burden for him, his wife and four children. He'd struggled with financing his legal fees as he fought his charges alongside Manafort, his long-time boss.

While keeping the public front that he was preparing for trial, Gates secretly hired a top Washington defense attorney to negotiate a deal with Mueller beginning in January 2018. The next month, Gates' new defense lawyer publicly announced his role the night before Gates walked into court to plead guilty to a much-reduced pair of crimes. He agreed to cooperate and began spilling what he knew of Manafort over more than 20 interview sessions with Mueller, his lawyer has said in court filings.

And he prepared to help the prosecution in the trial of his former boss.

Manafort march to trial

About a month before Manafort was set to go to trial, prosecutors revealed they had followed conversations between him and his Russian associate Konstantin Kilimnik as they attempted to get in touch with their lobbying contacts and shape what they might tell investigators. As a result, both Kilimnik, now living in Moscow, and Manafort were indicted for witness tampering . A federal judge revoked Manafort's house arrest, putting him in near-solitary detention in Virginia. He has stayed under those conditions since then.

Kilimnik also surfaced when another witness was charged with lying : Alex van der Zwaan, a Dutch lawyer who worked with Manafort and Gates on a public relations strategy in Ukraine. In a filing detailing how van der Zwaan covered up what he knew about communications in 2016 between Kilimnik and his Ukrainian lobbying partners, Mueller slipped in a key detail the FBI had learned: In 2016, Kilimnik had ties to Russian intelligence.

Manafort's trial began in Alexandria, Virginia in late July 2018. Prosecutors detailed the trappings of Manafort's luxurious life -- fine clothes, expensive rugs, landscapers and contractors -- to outline how he got rich in Ukraine, then hid the money in foreign bank accounts and used the cash to support his lavish spending. They showed dozens of emails, including one where Manafort wrote to Gates "WTF? ... You told me you were on top of this," regarding keeping his tax payments artificially low.

Gates took the stand against his former boss over three days of the trial. The questioning badly damaged Gates' credibility, after he admitted to stealing from Manafort — possibly from the Trump political operation, too — and said he had an affair . But the damage was worse for Manafort. Gates detailed how Manafort had orchestrated years of financial fraud.

After deliberating for about four days, on August 21, the jury convicted Manafort on eight financial fraud charges. The jurors couldn't agree unanimously on 10 other financial charges — but among them, only one juror had doubt of Manafort's guilt.

In an extraordinary bit of timing, the same hour a jury in Virginia read its guilty verdict for Manafort, Trump's long-time lawyer and fixer, Michael Cohen, pleaded guilty in Manhattan federal court to several financial crimes including tax fraud and campaign finance violations. Crucially, in his plea, Cohen implicated the President , whom Cohen told the court had directed him to pay hush money in the final days of the campaign to women who were alleging affairs with Trump. Trump has denied the affairs.

In the span of an hour, Mueller had secured a conviction of Trump's former campaign manager and the long-time personal lawyer to Trump had turned against the President. Cohen began meeting with Mueller's team and eventually pleaded guilty to an additional lying charge. Mueller's subsequent case against Cohen revealed that the Trump Organization and Trump's family had worked on a plan to develop a Trump Tower in Moscow throughout the first half of 2016 while Trump campaigned for the presidency — much further into 2016 than Cohen had testified to Congress in 2017 and that Trump publicly claimed.

Things speed up

With Manafort damaged and Cohen on board, Mueller moved many of his cases toward their final positions. Manafort was headed for a second trial in DC about his Ukrainian lobbying and dozens among Washington's elite were lined as possible witnesses. Manafort — after holding prosecutors off for 11 months — finally admitted to his crimes in September 2018 and agreed to cooperate with Mueller.

Papadopoulos' and Flynn's criminal cases also fast-tracked to a close in the fall of 2018. Prosecutors said Papadopoulos had never really been helpful to them and had even thwarted their ability to question the mysterious foreign professor who knew about the Russians' "dirt" on Clinton before it was released. Papadopoulos got two weeks in prison.

Flynn, on the other hand, had proven more useful. Mueller's team told a federal judge their well-known cooperator deserved no jail time because he had contributed substantially to ongoing investigations.

Flynn's cooperation "likely affected the decisions of related firsthand witnesses to be forthcoming" with investigators, Mueller's team wrote

With that assertion about other witnesses, Mueller put a point on what had become most perilous for so many defendants during the probe: Significant lies would be charged as crimes.

Flynn readied for his sentencing in December . The hearing started like any other, with prosecutors and defense counsel on friendly terms. But the judge, Emmet Sullivan of the US District Court for the District of Columbia, came ready with tough questions. Sullivan was appalled by Flynn's actions, especially while the military leader sat in the West Wing speaking with the FBI. Sullivan asked whether Flynn could have been charged with treason. Did Flynn realize how he had disgraced the American flag?

The special counsel's office said no, treason was never a line Flynn crossed-- and Sullivan said he had misunderstood the timeline of Flynn's private lobbying. But Sullivan's lecture left its mark. Flynn's attorneys realized the peril for their client in that charged moment and asked the judge not to sentence him that day. Flynn has finished cooperating with the investigation, prosecutors have said, but may still be of use as a witness in another case brought by the Justice Department against his former lobbying partner. Flynn's sentencing has not yet been rescheduled.

Cohen, too, received a sentence. He'll go to prison in May for almost three years for his financial fraud crimes. For lying to Congress, he got two months in prison, though that time won't make the time he serves lengthier.

At Cohen's sentencing, also in December, Mueller prosecutor Jeannie Rhee spoke about "core Russia-related issues under investigation" for which Cohen gave "credible and reliable" information. This statement still hasn't been explained.

But what Cohen knows and did for Trump has clearly been a live current throughout Mueller's tenure. The special counsel's office got access to his campaign-time and earlier emails beginning in July 2017- two months after Mueller's appointment. Other parts of Justice Department investigations involving Cohen are still under seal.

There are additional unresolved questions. Cohen has alleged in public testimony to Congress that he overheard Trump and Roger Stone speaking during the campaign about Wikileaks emails that could hurt the Democrats. Trump and Stone have denied the conversation happened.

Stone zone

With seven defendants sentenced or heading that direction and two dozen Russians charged, Mueller had one more case to unlock.

Stone, Manafort's former lobbying partner-turned-Republican spin doctor, awoke to a swarm of FBI agents on his lawn in Fort Lauderdale, Florida, on January 25, 2019. CNN had tracked the grand jury foot traffic for months and positioned a camera crew on Stone's lawn early that morning, with the possibility an indictment was coming. "FBI, warrant," the heavily armed agents yelled as they knocked on Stone's door just after 6 a.m. that day.

The arrest caught on tape became one of the most viral moments of Mueller's work. Stone had been charged under seal the day before by the grand jury in the DC courthouse for obstruction, lying during a congressional proceeding and threatening witnesses who might have contradicted his congressional statements. Mueller alleged that Stone attempted to reach WikiLeaks during the 2016 campaign about the stolen Democratic emails and that Stone wanted to understand the "dirt" the hackers found before new batches dropped. The most tantalizing allegation Mueller leveled against Stone was that he was "contacted by" senior Trump campaign staffers also keen on learning about what WikiLeaks might drop to hurt Clinton.

The Stone criminal case is ongoing. Stone has pleaded not guilty and is under strict orders not to speak publicly about the case, the court or Mueller.

'Heart' of the Investigation

Just after Thanksgiving 2018, prosecutors revealed another bombshell development : They believed Manafort was lying to them and the grand jury . This left Manafort with little leverage. He was already in jail and no longer useful to prosecutors. It was time for him to be sentenced.

Manafort, now grayed after eight months in jail and using a wheelchair, said he never intended to lie. Prosecutors submitted more than 800 pages of evidence suggesting he did, and the judge agreed.

In a filing leading up to the decision , Manafort's attorneys redacted their document badly, allowing the public to copy and read text beneath the blacked-out sections in digital copies. That text said Manafort had discussed with Kilimnik about a Ukraine peace plan and had shared 2016 polling data with him. The polling data revelation, especially, sent the Trump camp dialing back their blanket "no collusion" claims.

"I never said there was no collusion between the campaign, or people in the campaign," Trump's personal defense attorney Rudy Giuliani said on CNN in response to the Manafort filing. "I said the President of the United States."

In one of the hearings about the lies, Mueller prosecutor Andrew Weissmann gave one more nod to where Mueller's been headed all along, which has still not been revealed in full. Manafort and Kilimnik had met on August 2, 2016, at a cigar bar in Manhattan while Manafort led the Trump campaign. They talked about their old contacts in Ukraine and about a policy idea for peace that touched on US sanctions against Russia -- the same idea Flynn had discussed with Kislyak after the election.

Judge Jackson pressed the special counsel's office on its apparent obsession with Kilimnik's efforts. "Why is that important?" she asked.

Weissmann responded with an answer that's still largely redacted in the court file. He began by saying, "Okay. So, I mean, this goes to the larger view of what we think is going on, and what we think the motive here is." Kilimnik had a Russian intelligence connection, Weissmann reminded her. Then he turned to Manafort, saying, "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."

Prosecutors have yet to close the loop on whether this meeting of great significance led them to something larger.

But they did earn hefty penalties time for Manafort. The former Trump campaign chairman was sentenced to a total of 7.5 years in prison , and is giving up $35 million of his assets in forfeiture to the US government and restitution to victims.

In his final report, Mueller is poised to answer this: Do Manafort and Kilimnik, Stone and WikiLeaks, Flynn and Papadopoulos, the hackers and the troll farm, and the Trump campaign and the Russian government have more than lies and coincidences in common?

The answers, for now, are still under seal.