And the episode shows how after Mr. Trump’s election, Mr. Manafort sought to cash in on his brief tenure as Mr. Trump’s campaign chairman even as investigators were closing in.

The Ecuadoreans continued to explore the possibility of Chinese investment, but with the United States Justice Department and intelligence agencies stepping up their pursuit of Mr. Assange and WikiLeaks, Mr. Moreno’s team increasingly looked to resolve their Assange problem by turning to Russia.

In the months after Mr. Moreno took office, the Ecuadorean government granted citizenship to Mr. Assange and secretly pursued a plan to provide him a diplomatic post in Russia as a way to free him from confinement in the embassy in London. (That plan was ultimately dropped in the face of opposition from British authorities, who have said they will arrest Mr. Assange if he leaves the embassy.)

Jason Maloni, a spokesman for Mr. Manafort, said that it was Mr. Moreno — not Mr. Manafort — who broached the issue of Mr. Assange and “his desire to remove Julian Assange from Ecuador’s embassy.” Mr. Manafort “listened but made no promises as this was ancillary to the purpose of the meeting,” said Mr. Maloni, adding, “There was no mention of Russia at the meeting.”

Late last year, Mr. Mueller’s team charged Mr. Manafort with a host of lobbying, money laundering and tax violations in connection with his consulting work for Russia-aligned interests in Ukraine before the 2016 election. Mr. Manafort was convicted of some of the crimes and pleaded guilty to others as part of an agreement to cooperate with prosecutors. But prosecutors said last week that he violated the deal by repeatedly lying to them. Mr. Manafort remains in solitary confinement in a federal detention center in Alexandria, Va., waiting for a judge to set a sentencing date.

The trip to Ecuador was part of a whirlwind world tour that represented the last gasps of Mr. Manafort’s once lucrative career.