The probe of Podesta and his Democratic-leaning lobbying firm grew out of Mueller’s inquiry into the finances of former Trump campaign chairman Paul Manafort, according to the sources. As special counsel, Mueller has been tasked with investigating possible collusion between the Trump campaign and Russia.

Manafort had organized a public relations campaign for a non-profit called the European Centre for a Modern Ukraine (ECMU). Podesta’s company was one of many firms that worked on the campaign, which promoted Ukraine’s image in the West.