Federal investigators sought cooperation from Paul Manafort’s son-in-law in an effort to increase pressure on President Donald Trump’s former campaign chairman, according to three people familiar with the probe.

Investigators approached Jeffrey Yohai, who has partnered in business deals with Manafort, earlier this summer, setting off “real waves” in Manafort’s orbit, one of these people said. Another of these people said investigators are trying to get “into Manafort’s head.”


Manafort, who is a focus of the broad federal and congressional investigations into Russian meddling in the 2016 presidential campaign, is also under investigation for his business and real estate transactions, including some that involve Yohai.

That probe has accelerated in recent weeks, according to one of the people familiar with it.

FBI agents conducted an early morning raid last month on Manafort’s home in Alexandria, Virginia, rousing him from sleep and seizing reams of material.

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Manafort has not been accused of any wrongdoing.

It is unclear if investigators have secured cooperation from Yohai, who also hasn't been accused of wrongdoing. A lawyer for Yohai didn’t respond to a request for comment.

A Manafort spokesman declined to comment. A spokesman for special counsel Robert Mueller also declined to comment.

Manafort’s team has repeatedly pushed back on suggestions he’s cooperating with federal investigators. “Paul’s been forthcoming, but he’s not a cooperating witness and any suggestion to that effect is silly,” Manafort spokesman Jason Maloni said in a July interview when asked about concerns from former colleagues that Manafort had turned against the Trump team.

People close to Manafort reiterated Wednesday that he has no plans to become a cooperating witness.

Another high profile Trump associate touched by the Russia probe has suggested he'd be willing to talk with federal investigators. Michael Flynn, Trump’s first national security adviser, asked for an immunity deal in March in which he’d testify to Congress. A lawyer for Flynn declined to comment on the Mueller probe.

Mueller’s targeting of both Manafort and his son-in-law over potential criminal wrongdoing is a familiar tactic in white-collar cases, commonly called “climbing the ladder.”

“Manafort is — on many levels — a key subject of the investigation and someone who might be leveraged to share information about others,” said one Washington-based white-collar attorney with a client involved in the Russia probe.

The approach involves finding a suspected crime — false statements on tax returns or loan applications, for example — and then offering leniency on prosecution in exchange for cooperation. “They always start with the people on the low end of the ladder and try to get information on someone high up on the ladder,” said William Jeffress, a white-collar attorney who represented Vice President Dick Cheney’s chief of staff, I. Lewis “Scooter” Libby, in the President George W. Bush-era Valerie Plame leak investigation.

Mueller would clearly have jurisdiction over any real estate dealings between Yohai, Manafort and Russians, Jeffress said. In addition, he could press Yohai for details on what he knows about Manafort’s role in the campaign.

Renato Mariotti, a former federal prosecutor, said cooperating witnesses are “often very significant to make your case” when it gets to trial.

“They can provide direct evidence of what the defendant said or did,” he said. “That’s usually far more compelling to a jury than just looking at documents.”

Mariotti also brushed aside comments by Manafort associates who insist the former Trump campaign manager has nothing about Trump that would matter to investigators. “I wouldn’t take much from it,” he said. “I’d take it with a grain of salt.”

He noted a number of potential politicians under investigation who have been less than candid with their public statements: perhaps most notably President Bill Clinton, who insisted that he didn’t carry on a sexual affair with White House intern Monica Lewinsky.

“That’s very often the case that people involved in wrongdoing aren’t candid with even their closest friends and associates and family because they don’t want to disappoint the people they’re closest to,” Mariotti said. “Sometimes they’re not even candid to their own lawyers.”

Daniel Lippman contributed to this report.