Rosenstein specifically told Mueller to look into Manafort, gave investigation additional authority

Court filings have revealed that Special Counsel Robert Mueller has even broader authority than the already extensive power granted by Rod Rosenstein to investigate the Trump campaign “and any matters that arose or may arise directly from the investigation.” In an August 2, 2017 memo, Rosenstein gave the special counsel authority to investigate Trump campaign chairman Paul Manafort for his efforts in the Ukraine, and his ongoing outreach to Russia.