Special prosecutor Robert S. Mueller III on Monday revealed charges against three former Trump campaign officials — including onetime campaign chairman Paul Manafort — marking the first criminal allegations to come from probes into possible Russian influence in U.S. political affairs.

One of the three men charged, former Trump foreign policy adviser George Papadopoulos, pleaded guilty earlier this month to making a false statement to FBI investigators who asked about his contacts with a foreigner who claimed to have high-level Russian connections. The agreement was unsealed Monday.

Court documents described extensive efforts Papadopoulos made to try to broker connections with Russian officials and arrange a meeting between them and the Trump campaign, though some emails show his offers were rebuffed.

The third person charged was Manafort's longtime business partner, Rick Gates.