The FBI began its Trump-Russia investigation in July 2016. Special counsel Robert Mueller picked up the probe in May 2017. This summer the investigation will enter its third year.

And we still don't know what's going on.

At least, we don't have any clear idea of whether Mueller has found enough evidence to answer the probe's primary question, which is whether the Trump campaign colluded with Russia to fix the 2016 election. Or even the probe's secondary question, which is whether President Trump obstructed justice in the collusion investigation.

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Mueller is so secretive that his lawyers hesitate to reveal, even to federal judges, what the investigation is about. When U.S. District Judge T.S. Ellis recently questioned whether Mueller had the authority to prosecute former Trump campaign chairman Paul Manafort on financial charges unrelated to the 2016 campaign, Mueller's lawyers explained that the true scope of the investigation is a super-duper secret and "was conveyed to the special counsel upon his appointment in ongoing discussions [with deputy attorney general Rod Rosenstein]."

In other words, we know the parameters of the investigation, your honor, but we don't have to tell you. The judge's incredulous reaction: "Come on, man."

Nevertheless, as Mueller reaches the one-year milestone of his part of the investigation, it is possible to piece together what we have learned so far, and how it might shape what is to come.

Collusion? What collusion?

The one thing we know for sure is who Mueller has charged with crimes. Mueller's supporters often point to the numbers as proof of the effectiveness of the investigation: 19 indictments or guilty pleas, plus three companies charged with felonies. Of the 19 people, 13 are Russians who were involved in a 2016 election troll factory. They are not expected to ever stand trial. Two more are small fries tangentially related to either Manafort or the Russian effort. All three companies are also Russian and are not expected to face trial, although there are indications one of them might challenge Mueller's charges.

That leaves four players from the Trump campaign. Three are big fish. Manafort was the campaign chairman, while Rick Gates was his deputy, and Michael Flynn was the campaign's national security adviser. The last player, George Papadopoulos, was by no means a big fish, but his brief, self-assigned contacts with people who might have been in league with the Russians were part of the reason the FBI began investigating the Trump campaign in the summer of 2016.

Here is perhaps the most important fact about all the cases: So far, no one has been charged or pleaded guilty to any crime that involved collusion, or conspiracy, with Russia in the 2016 campaign.

Flynn pleaded guilty to lying about a perfectly legal phone conversation he had with the Russian ambassador during the transition. Papadopoulos pleaded guilty to lying about the timing and nature of his contacts with people who might have been connected to Russians. Gates and Manafort were charged with extensive financial crimes, including tax evasion and money laundering, but Gates was allowed to plead to far lesser offenses in return for cooperating with Mueller. Manafort is scheduled for trial in July.

What do all the cases have in common? As Trump might tweet, "NO Collusion!" If there were a collusion or coordination scheme between Trump and the Russians, it seems reasonable to guess that Manafort, Gates, and/or Flynn would have been part of it. Yet all have been investigated and charged, and none has been accused of collusion-related crimes.

Which suggests to some experts that perhaps there was simply no collusion, conspiracy, nor coordination scheme in the first place. "When a prosecutor has a cooperator who was an accomplice in a major criminal scheme, the cooperator is made to plead guilty to the scheme," former federal prosecutor Andrew McCarthy wrote last year. "This is critical because it proves the existence of the scheme." So far, Mueller hasn't done that.

Of course, just because Mueller hasn't done something yet doesn't mean he won't do it in the future. So collusion may still lie ahead. But where?

We can find clues on Mueller's direction by looking at what he hasn't done so far. For example, there have been no charges related to the infamous June 9, 2016 Trump Tower meeting in which a Russian lawyer, Natalia Veselnitskaya, lured Donald Trump Jr., Jared Kushner, and Manafort to a meeting by promising dirt on Hillary Clinton. The meeting has been called smoking-gun evidence of collusion, yet Mueller has not charged Trump Jr. or Kushner with any crime, nor Manafort with any crime related to the meeting.

Mueller has also not charged anyone in connection with two of the truly key events of the whole affair, the hacking of the Democratic National Committee and of Clinton campaign chair John Podesta. At least one Trump-related figure whom Democrats have accused of involvement in those incidents, Roger Stone, says he has not talked to Mueller's prosecutors nor even been contacted by Mueller's office. What does that mean? It means it's hard to say where those collusion-related parts of the investigation stand, other that they will have to be addressed at some point.

New Strategy

Meanwhile, in the White House, the president made a significant change recently in his strategy for dealing with Mueller. In short, he's switched from playing ball to playing hardball, Bill Clinton-style.

Under the advice of now-departed lawyers John Dowd and Ty Cobb, Trump took an accommodating stance. He mostly cooperated with the special counsel, choosing not to claim privileges and resist turning over requested documents, or block the testimony of some witnesses.

That was a big change for those old enough to remember the battles of the Bill Clinton years, when Clinton used all the privileges of the executive, including some he just made up, to frustrate independent counsel Kenneth Starr. Up until now, that just hasn't happened in the Trump White House.

But now Dowd and Cobb are gone, and Trump has taken a more confrontational, Clintonesque approach toward Mueller. While new lawyer Emmet Flood works the inside game, lawyer/spokesman Rudy Giuliani works on television. Amid all the discussion of how Giuliani messed up the Stormy Daniels issue — and he appears to have made more, not fewer, problems for Trump in that regard — Giuliani's main job on the public stage is to push back against Mueller and his prosecutors.

"It's the Mueller part of the case that I came for," Giuliani said on ABC recently. In an appearance on Fox News, Giuliani explained that the episode in Judge Ellis' courtroom revealed misconduct by the Mueller team that he, Giuliani, plans to highlight. "It kind of gives the American people a glimpse of what we have to deal with day in and day out, with the abuses," Giuliani said. "Not so much of Bob Mueller, but the people that work for him. I mean they're way over the top."

Trump himself has gone after the Mueller team, calling them (in a tweet of course), "the 13 Angry Democrats in charge of the Russian Witch Hunt." The number was incorrect — it appears to be closer to eight — but there's no doubt some of the prosecutors are active supporters of the Democratic Party. Andrew Weissmann, a top Mueller aide, actually attended Hillary Clinton's election night party in New York, and in internal memos early in the Trump administration praised resistance to the new president.

There is some evidence that the White House critique of the Mueller team is catching on. Three recent polls, from Monmouth, Marist, and Quinnipiac, all found that the number of voters who express positive feelings for the investigation is going down. Monmouth found that 54 percent of those surveyed said Mueller's investigation should continue, which is down from 62 percent last summer. Marist found that 45 percent agreed with the statement that Mueller has been "fair" to Trump, which is down from 53 percent earlier this year. And Quinnipiac found that 54 of those surveyed said that Mueller is "conducting a fair investigation," down from 60 percent last November.

Those are good numbers from Trump's point of view. But the credit may belong more to Mueller than to the Trump team. The biggest factor creating public doubts about Mueller could be the fact that his investigation appears to be dragging on without definitive results. Americans have been hearing the charge that Trump was in bed with Russia since the summer of 2016. Sometimes it has been difficult to hear anything else. Taken together, Mueller, and the FBI before him, have been on the case for quite a while. Perhaps the voters represented in the polls believe that Mueller should have come up with something by now. And if the process continues — and remember, Mueller has no time limit on his work — it's possible a large number of Americans could come down with a full-blown case of Mueller fatigue.

Investigating the investigation

If Mueller fatigue develops, it will also be due to a multitude of revelations of questionable conduct and political motives in the Trump-Russia probe. Those revelations, unearthed by a small group of Republican lawmakers in the House and Senate, focus mostly on the FBI investigation that preceded and formed the basis of Mueller's probe. But the collateral damage hits Mueller, too.

Start with the Trump dossier, the collection of "salacious and unverified" allegations against Donald Trump. ("Salacious and unverified" are the words of fired FBI director James Comey.) The dossier was funded by the Hillary Clinton campaign and the Democratic National Committee, but what astonished Capitol Hill investigators was the discovery that when Christopher Steele, the former British spy who compiled the dossier, took it to the FBI in the summer of 2016, the bureau offered to pay Steele to continue the work. Even though the deal ultimately fell through, having the FBI sign on to an anti-Trump opposition research project at the height of a presidential contest was a jaw-dropping development. And it undoubtedly damaged the bureau's reputation for fairness and the reputations of the FBI officials behind it.

Two more developments in the dossier story made things even worse. Even though the dossier's allegations had not been proven, the Justice Department used it as the basis for a (successful) application for a warrant to spy on former Trump campaign volunteer Carter Page. Suffice it to say that the nation's most powerful law enforcement institution is not supposed to use sketchy political opposition research as the basis for wiretapping Americans. The episode gave birth to the Republican-coined term "FISA abuse," taken from the Foreign Intelligence Surveillance Act that the Obama administration used to wiretap Page.

Then, in January 2017, the nation's top intelligence chiefs — Comey, John Brennan, James Clapper, and Mike Rogers — hatched a plan to have Comey brief president-elect Trump on the dossier's most salacious allegation, the "golden showers" tale of Trump involved in a kinky sex scene with prostitutes in Moscow in 2013. The January briefing was the first time Trump ever met Comey face-to-face, and the FBI director's opening message was: We know about you and those hookers in Moscow. (Never mind that the dossier's compilers had little faith in the sex story; Christopher Steele himself said there might be a 50-50 chance of it being true.) A few days after the Comey-Trump meeting, the story leaked to the media, whereupon Buzzfeed published the entire dossier. Voila! All the dossier's allegations were out in public. Trump believed he had been played by the nation's top law enforcement and intelligence officials — and who could doubt that he had?

Then there were the questionable actions in the case of Trump national security adviser Michael Flynn. During the transition, Flynn's conversation with Russia's then-ambassador, Sergey Kislyak, was not only perfectly legal — it was the type of thing a high-ranking, incoming national security official would be expected to do. But the Justice Department suspected that Flynn's contacts with Kislyak violated the Logan Act and sent the FBI to question Flynn in the White House. The problem was, the Logan Act was passed in 1799 and had never been used to successfully prosecute anyone, ever. No one had even tried in more than 150 years. It is also likely unconstitutional. Many legal experts consider it a dead letter, and in the Flynn context, it appeared the Obama Justice Department used the Logan Act as a pretext to investigate Flynn, when Flynn's real offense was his administration's intention to overturn some of Barack Obama's policies.

What's more — and the public didn't learn this until a year after the fact — the FBI agents who questioned Flynn did not believe he lied to them. Comey revealed that to Congress in March 2017, although he would later deny it publicly. In any event, Mueller still pursued Flynn for lying to the FBI, to which Flynn pleaded guilty last November. And then, a short time after the guilty plea, the judge in the case recused himself without explanation. It would be an understatement to say there is an air of mystery about the Flynn case. To this day, the public has no idea what happened.

Then there is the bizarre secrecy around the Comey memos, the FBI director's accounts of his conversations with the president. Mueller's office and the Justice Department treated them as if they were among the nation's most closely-guarded secrets. The memos were not only kept from the public; very few lawmakers with congressional oversight authority were allowed to see them, and then only in a room with an FBI minder present, with no copies or note-taking allowed. When, under pressure from Congress, the Justice Department released them, with minimal redactions, many wondered: what was all the secrecy about? That question could probably apply to much of the investigation.

Finally, there are the texts. Last December, the Washington Post reported that Mueller had demoted Peter Strzok, the deputy head of counterintelligence at the FBI who was playing a key role in the Trump-Russia investigation and who before that had played a key role in the Hillary Clinton email investigation. Strzok had exchanged thousands of text messages with a top FBI lawyer, Lisa Page, with whom he was having an extramarital affair.

The texts betrayed a deep anti-Trump bias. "God, Trump is a loathsome human," one text said. Other texts called Trump an "idiot" and a "d*uche." Still others referenced a conversation about an "insurance policy" in case of a Trump victory, which Republicans interpreted as a plan to pursue Trump in the unlikely event voters chose him to be president. Page left the Mueller investigation (and, recently, the FBI altogether) while Strzok was demoted to the human resources department — a serious comedown for a top counterintelligence official. But their texts, on top of the "13 angry Democrats" charge, left an unmistakable taint of bias on the Mueller team.

Taken together, the dossier, the treatment of Flynn, the handling of the Comey memos, the Strzok-Page texts, and more have cast legitimate doubt on Mueller's probe. When the president calls the investigation a "witch hunt," he's not making it up out of thin air.

The investigative arm of Congress

Mueller's assignment, whatever its details, requires that at the end of his investigation he submit a report on his work to the attorney general, or in this case to Rosenstein, because Attorney General Jeff Sessions has recused himself from Russia matters. That report will undoubtedly end up in the hands of Congress.

If the political gods smile on Republicans and the GOP keeps the House in November, it's likely nothing will happen. But if the polls pointing toward Democratic victory in the midterms are correct, a Democratic House majority will undoubtedly debate whether to impeach the president. If they go forward, it will be on the basis of Mueller's report. In that sense, the special counsel's main job today is to serve as the investigative arm of Congress.

But what would Democrats actually do? The answer, of course, depends on what is in the Mueller report. But if the question were up for consideration today, there would not be strong support in the general electorate for impeaching Trump. A recent Quinnipiac poll found that 38 percent of all voters surveyed would like to see Democrats impeach Trump, if the party wins the House in November. That's a worrisome number for Trump, but nowhere near overwhelming support for impeachment. The problem for Democrats is that there is overwhelming support in the Democratic base for impeachment; the Quinnipiac poll found that 71 percent of Democrats would like to see a Democratic-controlled House go after the president.

For now, at least, Democrats are stuck between their eager-to-impeach base and the larger electorate. It is unclear how they will strike the right tone in the coming campaign. If the polls on impeachment remain relatively unchanged, they can't very well campaign pledging, "Elect us and we'll impeach the president." The problem is, that is exactly what the Democratic base wants to hear.

Back in 2006, when some Democrats wanted to impeach President George W. Bush (who had a lower job approval rating than Trump does today), Nancy Pelosi, campaigning in hopes of becoming Speaker, declared impeachment "off the table." When Democrats won in November 2006, Pelosi kept her word. But that was a long time ago, in another world. Today, the party base is stoked for impeachment, and it will be hard for Democratic leaders to ignore what their voters want.

To talk or not to talk

Any impeachment decisions are months away. The question for the White House now is, what will Mueller do next? That's where the darkness around the Mueller investigation can be a real problem; not knowing what Mueller has done so far makes it impossible to know what he has left to do. And that makes it impossible to estimate how long it will take him to do it. Is Mueller three-quarters of the way through his investigation? Two-thirds? Half? No one outside the Mueller team knows.

One possibly encouraging note for Trump is that, at least as far as investigating the president himself is concerned, Mueller does not seem to have gone down any new, previously unknown trails. When the New York Times recently published a leaked list of 48 questions that Mueller's lawyers have proposed for a possible Trump interview, the questions focused on topics that have been discussed — and discussed, and discussed — for the last year.

Mueller wants to know about Trump's knowledge of Michael Flynn's actions. About Trump's dealings with Comey. About Trump's relations with Sessions. And about the Trump Tower meeting and a variety of previously-reported topics on the campaign's alleged contacts with Russians. That's all stuff the Trump team has known about for a long time.

The problem, of course, is that actually asking the president those questions — should he ever agree to an interview — would take a long time, precisely the kind of marathon interview the president does not want. "You don't just ask, 'What did you know about the Trump Tower meeting?' and he tells you the answer," former Whitewater prosecutor Paul Rosenzwig told the Times. "With 48 questions like that, that's honestly a two-day interview. That's 12 hours of questioning."

Not gonna happen.

Whether to talk to Mueller at all is the biggest looming question in the Trump-Russia probe. Trump's team is giving every indication that the answer will be no, but there could be some sort of compromise — limits on the time and scope of the questioning, allowing Trump's lawyers to be present, or other Mueller concessions — that might persuade Trump to say yes. Or Mueller might take a hard line, Trump might refuse, and the two sides end up in court, with uncertain results, extending the investigation's length in the process.

That's where the mystery surrounding the Mueller investigation comes into play once again. How can anyone predict what will happen when no one outside the Mueller office knows what the prosecutor has? So much talking-head speculation about the case is based on unfounded assumptions that Mueller has reams of evidence that, if revealed, would bring down Trump, or that Mueller has almost nothing, or that this or that cooperating witness knows everything, or knows nothing. The only thing certain in the whole affair is that the sooner it is over, the better — for all sides.

