Manafort's past clients included notorious dictators, kleptocrats and human rights abusers.
Special counsel Robert Mueller has submitted a long list of witnesses, including Rick Gates and Tad Devine.
The former Ukrainian president was named in the indictment of Trump's former campaign chair.
Former MP Denis Voronenkov was helping the Ukrainian authorities build a treason case against Yanukovich, Ukraine’s pro-Russia former president.
Of the many foreign policy pots and pans left neglected on the next President's stove, the one marked "Ukraine" may be ready to boil over.