As the summer drew to a close, Labor Day attained almost mythic status for followers of the Mueller investigation. Trump attorney Rudy Giuliani repeatedly claimed that the Mueller probe, which is looking into Russian interference in the 2016 election, was poised to wrap up by the beginning of September. Others breathlessly predicted that indictments of Roger Stone and even Donald Trump Jr. were imminent.

Instead, none of that happened. And now Mueller-watchers may have to wait even longer to learn what the special counsel investigation has in store. With the midterm elections less than 60 days away, some observers have predicted that Mueller will refrain from taking steps that could affect the outcome — although as former FBI director James Comey can attest, there’s no ironclad rule forbidding Department of Justice officials from taking action, even on the eve of an election.

As we enter this possible quiet period, however, it’s a good time to take stock of what Mueller has accomplished so far, and what questions are left unanswered.

The special counsel investigation tends to be described as a single, sprawling entity, with many details still in shadow. But there are several distinct tracks or areas of focus within the investigation that Mueller is pursuing simultaneously. Sketching out the trajectory of these tracks can help illuminate the special counsel’s strategy so far — and where it might go next. Legal experts say the special counsel is closing in on the parts of the probe that have the biggest impact for Trump and the people in his orbit.

Pre-existing illegal activity by Trump associates

So far, the longest-running element of the Mueller investigation — the indictment and trials of former campaign Trump campaign chairman Paul Manafort for financial crimes and foreign lobbying violations — is the thread that has the fewest obvious connections to the president. Manafort was already under surveillance by the FBI in connection with these crimes when he was working for the Trump campaign, and many of the crimes for which he was indicted took place before 2016.

Manafort was found guilty on eight counts, and his conviction could prove relevant for other parts of the investigation if he provides information about coordination between Trump campaign officials and Russian agents in 2016 in exchange for a more favorable sentence. But Lisa Griffin, a former federal prosecutor and law professor at Duke University, said the “window is closing” for that kind of cooperation. According to some reports, Manafort sought a plea deal for his second trial, which could have led to cooperation, but the talks broke down.

Russian coordination with the Trump campaign

The splashiest moments of the Mueller investigation so far have been the two sprawling sets of charges issued by the special counsel’s office against 25 Russian nationals and three Russian businesses. These documents allege that the Russians engaged in a complex, yearslong cyber-influence and hacking campaign with the explicit intent of undermining Hillary Clinton and supporting Trump in the 2016 election.

These individuals and businesses are highly unlikely to see the inside of a U.S. courtroom. But the indictments are important because they offer detailed evidence that Russians were actively working to buoy Trump’s candidacy, despite the president’s protestations to the contrary, and that they did it by sowing discord, spreading misinformation, and leaking damaging hacked materials about his opponent.

The charging documents pointedly stopped short of saying that the Russian efforts tipped the election to Trump, or that Trump campaign officials knowingly coordinated with the Russian agents. Legal experts, however, say that it’s entirely possible that the indictments of the Russians are just the foundation for future charges against Americans who may have solicited or participated in the circulation of the hacked materials or offered favorable treatment on issues like sanctions in exchange.

The question is whether these Americans — if they exist and are charged — were affiliated with the Trump campaign and how close they are to the president. One frequently discussed possibility is that Roger Stone, an informal Trump advisor who has been under scrutiny for some time because of his murky links to people responsible for hacking and leaking the Democrats’ emails, will be indicted.

Stone, who formally cut ties with Trump in 2015, was a relatively minor figure in the president’s campaign. But the indictment of anyone affiliated with the president for crimes related to election interference could mark a turning point in the investigation, which so far hasn’t addressed the question of whether Americans knowingly worked with Russians to influence the outcome of the election. And it’s still possible that higher-level members of the Trump campaign — even the president or his children — could eventually be implicated.

Obstruction of justice

Mueller’s reported probe into potential obstruction of justice has the most obvious implications for the president, although there have yet to be any charges that are directly linked to obstruction. Some experts, like Griffin, say that from a purely legal standpoint, there is plenty of publicly available evidence that Trump attempted to obstruct law enforcement in their investigation of Russian interference in the 2016 election — whether it was through his firing of former FBI director Comey (which the president himself said was related to “this Russia thing”) or tweets calling on high-level officials in the Department of Justice to end Mueller’s probe. That’s in addition to any other evidence Mueller may have gathered from Trump administration insiders like former White House counsel Donald McGahn.

“This part of the investigation should be easy for Mueller — it’s not nearly as complex or labor-intensive as unraveling what was happening with that Russian troll farm,” said Samuel Buell, a professor at Duke Law School and a lead prosecutor on the Enron case.

In fact, collecting evidence to support an obstruction case against Trump might actually be a less knotty problem for Mueller than determining whether he can win the case in court. Some are skeptical about whether Trump’s threatening tweets can actually constitute criminal behavior. And then there’s the question of whether Mueller would actually charge the president with obstruction of justice. It’s not clear, for example, whether it’s even possible to charge a sitting president with a crime.

But Mueller can also include evidence of obstruction in his ultimate report to the Department of Justice — which could be fodder for Congress to bring impeachment charges.

Other crimes committed during the investigation

For months, Trump has been toying with the idea of sitting down for a formal interview with Mueller. Buell says that he doesn’t expect this to happen. There’s simply too much danger that the president would lie under oath.

“In any moderately complex federal investigation, you always end up with some people who get in trouble for lying,” he said. So far, several of the people charged in Mueller’s investigation have already fallen into this category, including former national security adviser Michael Flynn, Dutch attorney Alexander van der Zwaan, and onetime Trump aide George Papadapoulos. Some of these defendants — like Flynn — are cooperating with investigators in other aspects of the investigation, but others, like van der Zwaan, appear to have been charged with perjury or making false statements simply to signal that lying to investigators carries consequences.

Mueller is reportedly allowing Trump to submit written answers to questions about whether his campaign coordinated with Russia to interfere with the election, which poses fewer risks. But that doesn’t mean Mueller won’t still push for an interview on questions related to obstruction. But will he subpoena Trump to appear before the grand jury if the president doesn’t agree to a voluntary interview? Whether a president can be subpoenaed in a criminal case is also unclear — and the inevitable legal battle that would ensue could carry more risks than benefits for the special counsel. (Brett Kavanaugh was asked about this very issue during his confirmation hearings Wednesday and refused to comment.) But refusing a subpoena could also play badly for the president, from both a political and legal perspective — even potentially forcing him to invoke the Fifth Amendment.

Ironically, the most concrete legal threat to Trump so far has come from outside the Mueller investigation. In August, former Trump attorney Michael Cohen pleaded guilty to making an illegal campaign contribution at the direction of the president. The charges against Cohen were brought by prosecutors in the Southern District of New York, who may be sharing information with Mueller but are operating independently from the special counsel.

Former prosecutors say it’s not surprising that Mueller is proceeding slowly and carefully when it comes to the parts of the investigation that have the biggest implications for the president. “This case is enormously complex,” Griffin said. “It involves international actors, complicated financial dealings, surreptitious communications — cases like this take a long time to develop under normal circumstances. And Mueller is operating under tremendous scrutiny. He’s going to want to build a rock-solid foundation before making any big moves.”

But whenever they occur, Mueller’s next announcement or round of charges could turn threats to the president that have so far been hypothetical into something very real.