WASHINGTON — President Donald Trump’s former campaign chairman, Paul Manafort, and a former Manafort business associate, Rick Gates, were indicted Monday on felony charges of conspiracy against the United States, acting as an unregistered foreign agent, and several other financial counts involving tens of millions of dollars routed through offshore accounts.

The unsealing of the indictment came the same day that Special Counsel Robert Mueller announced that a former Trump campaign aide had pleaded guilty to lying to FBI agents about the timing and detail of his attempts to line up meetings between Russian government officials and the Trump campaign.

The plea by George Papadopoulos marked the first criminal charges that cite interactions between Trump campaign associates and Russian intermediaries during the 2016 presidential campaign.

The charges brought Mueller’s sprawling investigation into a new phase, with campaign aides including the man who once led the president’s campaign facing felony charges and possible prison sentences.

Papadopoulos’ plea occurred on Oct. 5 and was unsealed Monday. In court papers, he admitted to lying about the nature of his interactions with “foreign nationals” who he thought had close connections to senior Russian government officials.

Manafort’s indictment doesn’t reference the Trump campaign or make any allegations about coordination between the Kremlin and the president’s aides to influence the outcome of the election in Trump’s favor. The indictment does allege a criminal conspiracy was continuing through February 2017.

The indictment filed in federal court in Washington accused both men of funneling tens of millions of dollars in payments through foreign companies and bank accounts as part of their political work in Ukraine. Manafort and Gates have plead not guilty to all charges. Both men appeared before a federal judge Monday in Washington.

The indictment lays out 12 counts including conspiracy against the United States, conspiracy to launder money, acting as an unregistered foreign agent, making false statements and several charges related to failing to report foreign bank and financial accounts. The indictment alleges that they moved money through hidden bank accounts in Cyprus, St. Vincent and the Grenadines and the Seychelles.

In total, more than $75 million flowed through the offshore accounts. Manafort is accused of laundering more than $18 million, according to the indictment.

A spokesman for Manafort did not immediately return calls or text messages requesting comment. Manafort and Gates have previously denied any wrongdoing. The White House declined to comment on the charges.

Manafort, 68, was fired as Trump’s campaign chairman in August 2016 after word surfaced that he had orchestrated a covert lobbying operation on behalf of pro-Russian interests in Ukraine. The indictments against Manafort and Gates were largely based on activities disclosed in August 2016 by The Associated Press, which reported that the pair had directly orchestrated a covert Washington lobbying operation on behalf of Ukraine’s ruling political party.

Citing internal emails, the AP noted that Gates personally directed the work of two prominent Washington lobbying firms. The indictment quotes from some of the same emails the AP had obtained.

The indictment accuses Manafort and Gates of orchestrating a nearly decade-long conspiracy to covertly work for Ukrainian interests and launder millions of dollars through offshore accounts. Specifically, the indictment accuses Manafort of using “his hidden overseas wealth to enjoy a lavish lifestyle in the United States, without paying taxes on that income.” That included using offshore accounts to purchase multimillion-dollar properties in the U.S., some of which the government is seeking to seize.

Mueller was appointed as special counsel in May to lead the Justice Department’s investigation into whether the Kremlin worked with associates of the Trump campaign to tip the 2016 presidential election.

The appointment came one week after the firing of James Comey, who as FBI director led the investigation, and also followed the recusal months earlier of Attorney General Jeff Sessions from the probe.

Mueller’s investigators have focused on Manafort for months. In July, they raided one of his homes in Virginia, searching for tax and international banking records.

Manafort joined Trump’s campaign in March 2016 and oversaw the convention delegate strategy. Trump pushed him out in August amid a steady stream of negative headlines about Manafort’s foreign consulting work.

Trump’s middle son, Eric Trump, said in an interview at the time that his father was concerned that questions about Manafort’s past were taking attention away from the billionaire’s presidential bid.

Manafort has been a subject of a longstanding FBI investigation into his dealings in Ukraine and work for the country’s former president, Viktor Yanukovych. That investigation was incorporated into Mueller’s broader probe.

Previously, he denied any wrongdoing related to his Ukrainian work, saying through a spokesman that it “was totally open and appropriate.”

Manafort also recently registered with the Justice Department as a foreign agent for parts of Ukrainian work that occurred in Washington. The filing under the Foreign Agents Registration Act came retroactively, a tacit acknowledgment that he operated in Washington in violation of the federal transparency law.

Mueller’s investigation has also reached into the White House, as he examines the circumstances of Comey’s firing. Investigators have requested extensive documents from the White House about key actions since Trump took office and have interviewed multiple current and former officials.

Mueller’s grand jury has also heard testimony about a June 2016 meeting at Trump Tower attended by a Russian lawyer as well as Manafort, Donald Trump Jr., and the president’s son-in-law, Jared Kushner.

In Gates, Mueller brings in not just Manafort’s chief deputy, but a key player from Trump’s campaign who survived past Manafort’s ouster last summer. As of two weeks ago, Gates was still working for Tom Barrack, a Trump confidant, helping with the closeout of the inauguration committee’s campaign account.

Correction: An early version of this post incorrectly identified Rick Gates in the headline. He is a former business associated of Paul Manafort, not Donald Trump.

Associated Press writers Michael Biesecker, Stephen Braun, Tom LoBianco and Jeff Horwitz contributed to this report. PBS NewsHour will update this story as it develops.

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