Federal prosecutors have lots of ways to intensify pressure on the people they're investigating, from early morning FBI raids to leaning on relatives of those under government scrutiny.
But even by those measures, the special counsel investigating Russian interference in last year's presidential election is moving with unusual speed and assertiveness, according to half a dozen legal experts following the probe.
Consider disclosures that FBI agents executed a search warrant last month for business and tax records at the suburban Virginia home of former Trump campaign chairman Paul Manafort. That step would have required them to prove to a judge that there's probable cause a crime has been committed.
Kenneth Starr, the Whitewater independent counsel frequently criticized for alleged overreach by then-President Bill Clinton, never utilized search warrants, two members of the team told NPR. Neither did the special counsel investigating the leak of a CIA operative's identity in the George W. Bush administration, said William Jeffress, a Washington attorney who represented White House aide Lewis "Scooter" Libby in that probe.
"A search warrant in a case like this is highly unusual," Jeffress said.
Lawyers said the special counsel may have been motivated to use a search warrant over concerns that evidence might be concealed or destroyed, which sometimes happens in terrorism and drug trafficking cases. Or, they said, Mueller may have been moving quickly amid a series of existential threats. In recent weeks, President Trump has blasted the Russia investigation as a "witch hunt" and flirted with the idea of firing Justice Department leaders as a roundabout way to get rid of Mueller himself.
Talking with reporters Thursday, the president said he was "very surprised" by the FBI raid at Manafort's home and said it sent a "strong signal." Trump also said that the White House is cooperating with the special counsel probe even though, he said, the subjects under investigation never happened.
In any case, the Justice Department frequently deploys tough tactics with a larger goal in mind: securing the cooperation of insiders who can guide authorities through a complex investigation and help deliver bigger targets.
"I call it 'climbing the ladder,' " Jeffress said. "It happens in every corporate investigation," where investigators question clerks and assistants, and then move up to vice presidents and higher-level executives.
A spokesman for Manafort, Jason Maloni, said he is responding to government inquiries.
Whether Manafort, former Trump national security adviser Michael Flynn or anyone else decides to strike a deal with the government is being closely watched by people in and outside the probe.
Authorities routinely enlist relatives to try to turn up the heat. Recent media reports suggested that investigators have reached out to Manafort's son-in-law, with whom he'd entered into some real estate dealings.
Indeed, several members of Mueller's 16-lawyer special counsel team have a long history of approaching lower-level figures, including spouses and in-laws, to build bigger cases.
Take Andrew Weissmann, a special counsel lawyer who once led the Justice Department's Enron Task Force. Prosecutors looking to uncover and punish fraud at that defunct energy company famously threatened to charge the wife of the company's chief financial officer with tax offenses if he did not agree to plead guilty and testify against his corporate superiors. The finance official, Andrew Fastow, refused. So, authorities indicted his wife, Lea. They both served prison time.
A more recent addition to the special counsel team, Greg Andres, helped bring to justice the Bonanno crime family boss as a young mob prosecutor in Brooklyn, N.Y. Through the course of the trial, Andres helped unravel dozens of crimes over three decades, using federal agents and members of the crime family as narrators. One of his key witnesses was the brother-in-law of the defendant, Joseph Massino.
"The story principally was told from the vantage point of those involved in the crimes at issue and their credibility was a crucial issue," Andres told the publication Law360 last year.
Andres so got under the skin of the mobsters that one later testified he had been targeted for a "hit."
ARI SHAPIRO, HOST:
The special counsel investigation into Russian interference in last year's election is heating up. This week we learned that the FBI conducted an early morning raid at the home of former Trump campaign chair Paul Manafort. Here's what the president had to say about it yesterday.
(SOUNDBITE OF ARCHIVED RECORDING)
PRESIDENT DONALD TRUMP: It's pretty tough stuff.
UNIDENTIFIED REPORTER: Mr. President...
TRUMP: You wake him up. Perhaps his family was there. I think that's pretty tough stuff.
SHAPIRO: NPR justice correspondent Carrie Johnson is here to bring us up to speed on the investigation. Hey, Carrie.
CARRIE JOHNSON, BYLINE: Hi, Ari.
SHAPIRO: Is it pretty tough stuff?
JOHNSON: Well, I interviewed lots of lawyers and experts this week. They said using a search warrant in a white-collar corruption case is unusual, more typical in drug trafficking or terror investigations. In fact Whitewater independent counsel Ken Starr, who received so much criticism about overreach during the Bill Clinton years, never used search warrants. I checked with two members of his team. They told me they didn't do it. Neither did Patrick Fitzgerald. He investigated the leak of a CIA operative's identity in the George W. Bush era. So this is out of character.
SHAPIRO: If it's so unusual, do we know why the special counsel used one in this case?
JOHNSON: We don't know for certain. Robert Mueller doesn't talk about ongoing investigations. But the best clue may be the affidavit an FBI agent filed in court to support this search. The agent had to convince a judge there was probable cause, some crime had been committed. That search warrant is not public, at least not yet.
But sources close to the case are saying investigators wanted bank and tax records from Paul Manafort, the one-time chairman of the Trump campaign. And a Manafort spokesman says he's responding to government inquiries from the FBI and Congress. Legal experts are telling me Mueller would not have used a search warrant if there were no concerns about cooperation or destruction of evidence. In other words, there was some signal that evidence might have been gotten rid of.
SHAPIRO: So Paul Manafort is clearly one focus of the investigation, but he may not be the only focus. What is the endgame here?
JOHNSON: Well, in big, complicated investigations like this one, the FBI and prosecutors want to find documents, emails, contemporaneous records of whatever they're investigating. But they also need insiders to explain those documents - the conversations, the motivations. Think of it like climbing a ladder, veteran Washington defense lawyer Bill Jeffress told me. Start with the office assistants and the clerks. Move up to the vice presidents and see how far things go.
Now, some of this pressure may be designed to get Paul Manafort to consider turning into a government witness cooperating with the special counsel and see what he has to say about other people under investigation. Right now there's no public sign that's happened yet.
SHAPIRO: Based on the people you've talked to, would that be a pretty common tactic for a special counsel to take?
JOHNSON: Absolutely. You know, this 16-lawyer team that Bob Mueller has put together to investigate...
SHAPIRO: That's a large number.
JOHNSON: Yeah, a large number, but the experience is unbelievable. These are people who have prosecuted terrorists, mobsters and very, very high-level corporate executives. They're not afraid to use tough tactics.
Now, consider a guy named Andrew Weissmann. He once led the Enron task force which prosecuted executives at that defunct energy company. At one point, they wanted the cooperation of the chief financial officer, Andrew Fastow. They threatened to indict Fastow's wife if he didn't cooperate with them. Fastow didn't blink. And so both the husband and the wife were prosecuted and did prison time.
SHAPIRO: So that's the team that these folks are up against.
JOHNSON: Not just Enron. Think about another more recent addition to this team, Greg Andres, a longtime prosecutor from Brooklyn, took down the Bonanno crime family boss. He put together a trial team and presented witnesses for weeks on end. He secured the cooperation of the crime family boss's brother-in-law who went on to testify against the crime family boss in court. And Greg Andres so got under the skin of these mobsters that one of them testified they wanted to take out a hit on him.
SHAPIRO: Wow. So this sounds like an all-star legal team. Do we know where they're going next?
JOHNSON: Well, we don't know for sure. They're going to be sifting through lots of documents, talking with witnesses. And then, Ari, we know there are now two grand juries looking at elements of this investigation - one in suburban Virginia, another in D.C. According to grand jury rules, prosecutors and FBI agents are not supposed to be talking about what's going on in those grand juries, but the witnesses sure can. So some of the information we're likely to see in the coming weeks may come from that.
SHAPIRO: That's NPR justice correspondent Carrie Johnson. Thanks, Carrie.
JOHNSON: My pleasure. Transcript provided by NPR, Copyright NPR.