Special Counsel Robert Mueller’s investigation into Paul Manafort, the onetime Trump campaign chairman, appears to be moving far more aggressively than any other part of the sprawling Russia investigation.

On Monday night, The New York Times reported new details about the July raid on Manafort’s Virginia home. Federal investigators broke into his house in the early morning hours, seizing documents and computer files about his extensive business dealings. The Times also reported that Mueller’s team told Manafort that he would soon be indicted, the first indication to date that the former FBI director will ultimately file criminal charges in his sweeping probe.

Soon thereafter, CNN reported that Manafort had been the target of a special warrant issued under the Foreign Intelligence Surveillance Act, or FISA, before and after the 2016 presidential election. The exact dates of his surveillance are unclear: CNN reported it began sometime after the FBI opened an investigation into his political consulting in 2014, ended in May of 2016, and then resumed sometime after the November election.

Manafort is the second known Trump campaign official against whom investigators reportedly secured a FISA warrant, which are used to target those believed to be agents of a foreign power or in contact with such agents. (The first former Trump campaign official revealed to be the target of a FISA warrant was adviser Carter Page.)

Taken together, the two reports suggest that Manafort could face serious legal trouble from Mueller’s probe. While they offer some new details on what has been a largely opaque inquiry into Russian electoral meddling, the two accounts also raise new questions about its scope and findings to date.

1. For what offenses would Mueller indict Manafort?

Compared to other members of the Trump inner circle, Mueller had a head-start on investigating Manafort. The special counsel’s team inherited a federal investigation into his foreign business dealings that dated back to 2014. Until then, Manafort worked as a lobbyist and consultant for pro-Kremlin political parties in Ukraine, including the party of then-Ukrainian President Viktor Yanukovych, a close ally of Moscow. Mueller’s primary responsibility is to investigate Russian interference in the 2016 presidential election, but he has broad latitude to pursue “any matters” he discovers during the course of his inquiry.

Taking over the long-running investigation could give Mueller leverage over Manafort in the overall Russia investigation. Many members of Mueller’s team have experience prosecuting complex white-collar crimes, including money laundering, bribery, and other public-corruption cases. Reports from the Times and other news outlets have hinted that investigators are focusing on Manafort’s financial and business records, including any documents that would be related to offshore banking accounts. Any charges filed against Manafort based on those probes could be used to bargain for his testimony in other aspects of the investigation. Manafort, for his part, has consistently denied any wrongdoing, and no formal criminal allegations have been made against him.

2. Why did the FBI get a no-knock warrant?

It’s been known since August that FBI investigators obtained what’s known as a “no-knock warrant” when it raided Manafort’s home in July. The Times account described the aggressive move as a “shock-and-awe tactic,” suggesting it was intended to prevent the destruction of evidence and send a message to subjects of the investigation. Such a move is notably more aggressive than any other steps Mueller has taken towards other persons of interest in the investigation.

When police obtain a typical search warrant, it’s assumed the officers will announce themselves when executing the search and explain what they’re looking for. A no-knock warrant skips this assumption. In these cases, investigators tell a judge they have probable cause to believe there’s evidence of criminal behavior and that they believe there’s a risk that evidence will be lost or destroyed if they announce themselves when trying to obtain it. It’s unclear how Mueller’s team demonstrated that risk to a federal judge.

At the same, a no-knock warrant’s implications shouldn’t necessarily be taken at face value. It’s true that such tactics are an unusual step in white-collar cases, especially against wealthy, politically connected targets like Manafort. At the same time, The Washington Post’s Radley Balko cited numerous accounts last month in which law-enforcement agencies used no-knock raids against impoverished and disadvantaged suspects with less discretion.

Without more information about why Mueller’s team opted for a no-knock raid, it’s hard to discern whether the move was grounded in practicality, theatricality, or a little bit of both.

3. What gave investigators probable cause to obtain a FISA warrant?

To obtain a FISA warrant to target a U.S. citizen, a federal investigator must demonstrate to the Foreign Intelligence Surveillance Court, a secretive tribunal in Washington, why he or she thinks the target is acting on behalf of a foreign government. If that standard is met, the court authorizes 90 days of surveillance, which can be renewed as long as the government can demonstrate its utility.

Stephen Vladeck, a University of Texas law professor, said it was a “big deal” that investigators had reportedly secured a FISA warrant against Manafort. “It means not only that the government thought it had probable cause that he was acting as an agent of a foreign power, but that it convinced a FISA judge that it was right,” he explained. “One can only speculate as to what evidence provided the basis for such a probable cause showing, but it certainly does not augur well for Manafort.”

4. With whom was Manafort talking during the time period he was under surveillance?

Obtaining a FISA warrant could give federal investigators access to a wealth of communications made by Manafort during the 90-day periods it authorized. That surveillance may answer some questions about possible Trump-Kremlin lines of communication and whether they existed. A tantalizing Times article in May reported that U.S. intelligence agencies had captured communications between Russian political and intelligence officials during the summer of 2016 in which they discussed ways to influence the Trump campaign. According to the Times’ descriptions of the intercepts, those conversations focused on reaching out to Manafort and Michael Flynn.

When the report was published, Manafort emphatically denied he had colluded with Russian officials to influence the election. The Times did not report at the time that any of those discussions among the Russians had borne fruit. But in July, the Times revealed that Manafort was among those who attended a previously unknown June 2016 meeting between Donald Trump Jr. and a Russian lawyer with ties to the Kremlin who claimed to have damaging information about Hillary Clinton.

5. Were any of his conversations with Trump recorded, either before or after the election?

Few of Trump’s claims have been as sensational as a series of tweets on March 4 alleging that Barack Obama had wiretapped Trump Tower prior to the election. His allegation that a sitting president had surveilled a political opponent reverberated throughout Washington, even though Trump provided no evidence to support his claim. Obama broke his post-presidency silence to deny the allegations and assert he had never directed the surveillance of any U.S. citizen.

Six months later, those claims remain unfounded. Earlier this month, the Justice Department formally asserted in federal court “that they have no records related to wiretaps as described by the March 4, 2017, tweets,” essentially disproving Trump’s allegations about a wiretap of his eponymous Manhattan skyscraper. But the surveillance of Manafort raises questions about whether any of Trump’s conversations could have been incidentally collected by investigators.

Trump frequently keeps in contact with former advisers even after they’re ejected from his inner circle. He’s reportedly stayed in touch with Corey Lewandowski, his original campaign manager, long after his departure from the team after physically attacking a reporter. Yahoo News and other outlets also reported Trump reached out to Flynn and urged him to stay strong as the retired general’s legal troubles began to mount. Manafort was no different: CNN reported Monday night that he and Trump stayed in touch after the inauguration until lawyers for both men cut off contact.

Depending on the time frame for the post-election FISA warrant, it’s possible some of those conversations could have been picked up. That said, even if Trump’s conversations were incidentally collected this way, it wouldn’t bear out his original claim of a politically motivated effort to spy on him in Trump Tower.