Why is paul manafort in the news?

Paul Manafort, President Trump’s former campaign chairman, pleaded not guilty to a variety of charges brought by Special Counsel Robert Mueller’s team.

Manafort has been the subject of a longstanding investigation over his dealings in Ukraine several years ago - for which he didn’t file as a foreign agent until June. But Mueller has incorporated that investigation into his own probe into Russia’s meddling in the 2016 election and possible collusion with Trump associates.