Mr. Manafort pleaded not guilty to those charges and additional charges related to his alleged failure to register as a foreign agent and conspiracy to launder money. A second trial for those charges was set for September in Washington.

Pleaded Guilty

Michael D. Cohen

Mr. Cohen, Mr. Trump’s former personal fixer and lawyer, pleaded guilty to multiple charges, including campaign finance violations, tax evasion and bank fraud.

The campaign finance violations relate to two payments Mr. Cohen said he made to two women during the 2016 campaign to prevent them from publicly airing their allegations that they had affairs with Mr. Trump. Mr. Cohen said Mr. Trump had requested the payments be arranged.

Mr. Cohen’s plea deal did not include a requirement that he cooperate with federal prosecutors. However, he can provide information or evidence to them or Mr. Mueller’s investigators later.

Pleaded Guilty and Known to Be Cooperating

George Papadopoulos

Mr. Papadopoulos, a former foreign policy adviser to the Trump campaign, pleaded guilty on Oct. 5 to lying to the F.B.I. about a conversation with a professor during which he was told that Moscow had “dirt” on Hillary Clinton and “thousands of emails,” according to court records. He was sentenced to 14 days in jail, fined $9,500 and ordered to complete 200 hours of community service and one year of probation after he serves his sentence.

Mr. Papadopoulos initially told investigators that he met with the professor, who has known ties to the Kremlin, before he joined the Trump campaign. In fact, the meeting happened days after he became a campaign adviser, and he repeatedly tried to arrange meetings between Russian government officials and the Trump campaign.

He has been cooperating with the Mueller investigation since his arrest last July at Dulles Airport outside Washington. Mr. Papadopoulos was the first person to plead guilty in the inquiry.