WASHINGTON (AP) — President Donald Trump’s former campaign chairman, Paul Manafort, and a former business associate, Rick Gates, surrendered to federal authorities Monday. That’s according to people familiar with the matter.

The charges are the first in special counsel Robert Mueller’s investigation into potential coordination between Russia and the Trump campaign. Details on the charges have not been released.

Manafort and Gates surrendered to federal authorities in Washington. They are expected in court later Monday to face charges brought by Mueller’s team. That’s according to one person familiar with the investigation. A second person said that Gates had worked out an arrangement to turn himself in on Monday.

The people spoke on condition of anonymity because they were not authorized to discuss publicly an ongoing federal probe.