Semion Mogilevich.
Head of the Ukrainian Jewish Mafia.
Friends with Oleg Deripaska, who Paul Manafort is friends with.
Did Manafort help oust his own boss?
John E. Herbst, director of the Atlantic Council’s Dinu Patriciu Eurasia Center, recalls a meeting requested by Manafort in early 2005. Herbst was serving as the US ambassador to Ukraine at the time.
Manafort told Herbst he would be working with Yanukovych. “That was something that I thought was a fine idea. As I said to him, ‘If you can help Yanukovych win an election fair and square, good,’” said Herbst.
https://www.atlanticcouncil.org/blogs/new-atlanticist/paul-manafort-s-ukraine-connection/