That part required the plaintiffs to notify any investigative agency with which they “may have previously cooperated” that they did not want to “participate in any investigation or criminal prosecution” related to matters in the lawsuit, according to a confidentiality agreement signed by more than 20 people. The plaintiffs could respond to a subpoena or court order, but would also have to notify the defendants that they had received it, the agreement said. The criminal investigation was closed sometime afterward.

As for Trump SoHo, the condo-hotel concept did not pan out. Only about a third of the units were ultimately sold, and one of the project’s lenders foreclosed on the rest, although the property remained open and became a popular luxury hotel, still managed by Mr. Trump’s company.

Mr. Sater left Bayrock after the news of his criminal background was reported. But even after that, his association with Mr. Trump did not end. The Trump Organization later gave him a business card identifying him as a “senior advisor” to Mr. Trump, as well an office. Mr. Garten, the general counsel for the organization, said that Mr. Sater was never an employee, but that he had worked independently to steer potential deals to Mr. Trump. The arrangement lasted about six months, Mr. Garten said. Mr. Sater declined to comment on his dealings with Mr. Trump or with Bayrock.

By the time Mr. Trump sat for a deposition in a lawsuit in November 2013, it was clear he no longer saw the benefit of knowing the Bayrock executives with whom he had once completed big deals. He said he barely knew Mr. Arif: “I mean, I’ve seen him a couple of times; I have met him.”

As for Mr. Sater, “if he were sitting in the room right now,” Mr. Trump said, “I really wouldn’t know what he looked like.”