US President Donald Trump's former campaign officials Paul Manafort, Richard Gates under house arrest

US President Donald Trump's former campaign chairman Paul Manafort and Richard Gates, Manafort’s close associate and business partner, have been put under house arrest after they pleaded not guilty to charges stemming from Justice Department special counsel Robert Mueller's extensive probe into whether Russia interfered in the 2016 US presidential election.

Gates, 45, and Manafort, 68, are accused of conspiracy, money laundering, failing to register as foreign agents and making false statements to investigators — even as they worked for Trump's presidential campaign. Both pleaded not guilty Monday.

In addition to Manafort and Gates, George Papadopoulos, the former Trump campaign foreign policy adviser, has been charged by Mueller, alleging that he had "close connections with senior Russian government officials."

Papadopoulos, circled, at a meeting with Trump in March 2016 (Trump campaign photo).

Papadopoulos was charged back in July and ultimately pleaded guilty in October to lying to federal agents investigating Russian interference in the presidential election about contacts he had with people he believed had ties to the Russian government while he was affiliated with Trump’s campaign.

Court papers of the case released on Monday revealed those contacts included an unnamed overseas professor whom Papadopoulos met in Italy in March, the same month he joined the campaign. In April 2016, the professor told him the Russian government had “dirt” on Democratic presidential candidate Hillary Clinton, including thousands of emails.

According to court filings, Trump was aware of Papadopoulos’s claims that he had pipeline to Moscow. During a March 2016 meeting in Washington of the campaign’s national security advisers, Papadopoulos said he had connections that could help arrange a meeting between the then-candidate and Russian President Vladimir Putin.

White House rejects indictments

White House press secretary Sarah Sanders said she was “not sure that the president recalls specific details of the meeting,” calling it “brief.” She described Papadopoulos’s role with the campaign as “extremely limited.”

Commenting on Manafort and Gates, she said they were not connected to Trump's campaign or his presidency.

The charges had "nothing to do with the president, nothing to do with the president's campaign or campaign activity" and proves there is "no evidence of Trump-Russia collusion," said Sanders.

She also said there is "no intention or plan to make any changes in regards to the special counsel" when asked about the possibility of Mueller being fired.

"We have been saying from Day 1 there has been no evidence of Trump-Russia collusion, and nothing from the indictment today changes that at all," she said.

Who is Manafort?

During Manafort and Gates’ time at the Trump campaign, Manafort forged close relationships with Trump’s children and quickly earned their internal support. Manafort’s authority over the campaign grew and, with the strong backing of the Trump family, he soon was named the campaign chairman.

Manafort feuded internally with campaign manager Corey Lewandowski as the two men jockeyed to gain control over campaign strategy and operations. In June 2016, Trump fired Lewandowski at the urging of Donald Trump Jr., Ivanka Trump and her husband, Jared Kushner.

Donald Trump (L), Paul Manafort (C) and Ivanka Trump are seen at the Republican National Convention in Cleveland. July 21, 2016. (Photo by Reuters)

Manafort assumed full control of the campaign, with Gates operating as his right hand. Together, they orchestrated the GOP convention in Cleveland, oversaw Trump’s vice presidential selection process and devised the campaign’s strategy for the general election against Democratic nominee Hillary Clinton.

After the 2016 presidential election Gates planned the inauguration, including fundraising, under Tom Barrack, Trump’s close friend and adviser.

Indictment details

The indictment against Manfort and Gates alleges that the two worked from 2006 to 2015 as unregistered agents for former ousted Ukrainian President Viktor Yanukovych – a close Russian ally who is currently in exile in Russia and wanted by Ukraine for high treason.

The two are also accused of trying to hide their involvement in lobbying efforts on behalf of the pro-Russian Yanukovych government to lobby members of Congress.

Manafort and Gates allegedly arranged for a third-party organization to be listed as the client of those lobbying services, when in reality it was controlled by the Ukrainian government, and made false statements to the Justice Department when asked about their role in late 2016 and earlier this year.

Then Republican candidate Donald Trump accompanied by Richard Gates July 21, 2016. (Photo by AP)

The 12 charges against the two men also include the laundering of millions of dollars that the two partners earned in order to hide their profits from US authorities.

"Manafort used his hidden overseas wealth to enjoy a lavish lifestyle in the United States, without paying taxes on that income," prosecutors alleged. "Manafort, without reporting this income to his tax preparer or the United States, spent millions of dollars on luxury goods and services for himself and his extended family through payments wired from offshore nominee accounts to United States vendors."

Money laundering, the most serious of the charges, carries a potential prison sentence of up to 20 years. However, the total maximum sentence for Manafort and Gates, if found guilty of all 12 counts, is 115 years in a federal prison.

What happens next?

Politico has asked legal experts including former federal prosecutors, law professors and practicing attorneys to consider where Monday’s developments would lead. Many of those asked said the three indictments are just the beginning of a long game that could potentially close in further on Trump’s inner circle.

Paul Rosenzweig, former deputy assistant secretary for policy at the Department of Homeland Security said “Everyone who sails into Trump’s orbit eventually gets burned. Today it is Manafort and his colleague Gates… In short, the game has just begun. Don’t expect a resolution anytime soon—this is just the bottom of the second inning in a long game.”

David Sklansky, a professor at Stanford Law School, said “the charges will make it a good deal harder for Trump and his supporters to dismiss the allegations of Russian involvement with his campaign,” leading to further charges against Trump confidants.

Lori E. Lightfoot, former assistant attorney in the criminal division of the US Attorney’s Office says the indictments do “not bode well for others associated with Trump’s campaign who have allegedly made similar false statements.”

Mark S. Zaid, a national security attorney in Washington, DC said "the indictments today of Manafort and Gates, along with Papadopoulos’ unsealed guilty plea, sends a potentially devastating message to Trump and his inner circle.”

“Given Trump’s history with legal matters, especially depositions, the danger for him to create criminal liability for himself seems astounding," he noted.