Robert Mueller is back.

After a quiet few months in the run-up to the midterm elections, the special counsel’s Russia investigation is heating up again with a string of tantalizing new details emerging this week.

None of it answers the central question: Did Donald Trump and his campaign coordinate with Russia to help him win America’s 2016 presidential election. But the new evidence does make clear that some in Trump’s orbit recognized his Russia connections were a problem — so they lied about them.

Mueller has indicated there are more criminal charges to come.

Here’s a look at the key lines of inquiry, what we know and what we don’t.

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WHAT’S THE LATEST?

It’s been a busy week.

On Thursday, Michael Cohen, the longtime Trump lawyer and legal fixer, pleaded guilty to lying to Congress about his efforts during the 2016 campaign to line up a Trump Tower Moscow project. The plea was significant because it prominently featured Trump and conversations he and his family had with Cohen about the project.

Prosecutors did not accuse Trump or his grown children of any wrongdoing. But Cohen said he lied to be consistent with Trump’s “political messaging.”

The surprise plea came just days after prosecutors revealed that former Trump campaign chairman Paul Manafort’s separate plea deal fell apart over allegations that he lied to investigators, a development that could lead to new charges .

Draft court documents made public this week also revealed that Mueller made a plea offer to Jerome Corsi, a conservative writer and conspiracy theorist. The documents accused Corsi of lying about his discussions with Trump confidant Roger Stone about WikiLeaks during the 2016 campaign.

American intelligence agencies and Mueller have said Russia was the source of hacked material released by WikiLeaks during the campaign that damaged Hillary Clinton’s presidential effort. Mueller’s office is trying to determine whether Corsi and Stone had advance knowledge of WikiLeaks’ plans.

Corsi has denied lying and rejected the plea offer. Stone has also denied having any contact with WikiLeaks or knowledge of its plans.

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WHAT DO WE KNOW FOR SURE?

There were a lot of contacts between Russia and people close to Trump. And the Kremlin mounted a large-scale operation that sought to hurt Hillary Clinton and help Trump, according to Mueller and U.S intelligence agencies .

In public court filings, Mueller has woven a narrative of events that he believes are significant. They include contacts between a little-known campaign foreign policy adviser and Russian intermediaries, conversations the president and his family had with Cohen about a proposed Trump Tower Moscow and contacts between senior advisers in Trump’s incoming administration and Russian officials during the transition period.

Much of that has become public because key participants — Cohen, ex-National Security Adviser Michael Flynn and ex-Trump campaign foreign policy adviser George Papadopoulos— lied to federal agents about it.

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WHAT REMAINS UNKNOWN?

Mueller has yet to answer definitively the central questions in the Russia probe.

Did any Trump associates coordinate with Russia in an attempt to sway the 2016 presidential election? And did the president cross the line and obstruct justice in his efforts to stymie the Russia investigation?

Mueller’s team is also intently focused on WikiLeaks and whether anyone close to Trump or his campaign knew in advance about the group’s plans to release the material hacked by Russia.

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WHO HAS BEEN ACCUSED OF CRIMES?

Thirty-three people and three companies.

Since Mueller’s appointment in May 2017, he’s obtained guilty pleas from seven people including five involved in the Trump campaign. Flynn and Papadopoulos both admitted to lying about their contacts with Russians or Russian intermediaries.

Mueller also brought a series of charges against Manafort over undisclosed foreign lobbying on behalf of Ukraine and millions of dollars that were never reported to the IRS. Manafort was convicted by a jury of eight felony counts. His right-hand man, Rick Gates, took a plea deal , and Mueller brought obstruction charges against Konstantin Kilimnik, a Manafort associate who prosecutors say has ties to Russian intelligence.

In addition, Mueller has brought sweeping indictments against Russians. That includes charging 13 Russians and three companies with orchestrating a covert effort to flood American social media with disinformation to sow discord during the U.S. election campaign. One company is fighting the charges. Twelve Russian intelligence officers were also accused of hacking Democratic organizations during the 2016 campaign.

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WHAT ABOUT TRUMP?

The president is angry to the point of boiling about the Mueller probe — and he’s hinted he may do something about it.

Trump has heightened his attacks in recent weeks, blasting the special counsel as corrupt and unethical. He’s even accused Mueller of pressuring people to lie.

In a tweet, Trump floated the idea of giving those caught up in the investigation some ”relief .” And this week, he said he hasn’t ruled out a pardon for Manafort.

All of this came as his attorneys turned over Trump’s written answers to Mueller’s questions about his knowledge of any ties between his campaign and Russia.

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WHEN WILL WE FIND OUT MORE?

It’s not clear.

Mueller’s indictments and guilty pleas are not announced ahead of time. The special counsel also hasn’t said when he will complete any report of his findings.

But there are several deadlines coming up where Mueller will have to disclose at least some new details about his investigation.

Next week, prosecutors will have to disclose what lies they say Manafort told them after he agreed to cooperate. Prosecutors will also have lay out the nature of the cooperation by Cohen and Flynn in the next few weeks.

All of those filings will be closely watched to see what they say about where Mueller is going.

(AP)