Special Counsel Robert Mueller’s inquiry into alleged Russian interference in the 2016 election is ongoing – and secret.

So far, four former Trump campaign associates – Michael Flynn, Paul Manafort, Richard Gates and George Papadopoulos – have been charged, though none of the charges are directly related to any misconduct by the president’s campaign.

The special counsel filed new tax evasion and bank fraud charges against Manafort and Gates in late February, potentially increasing the amount of prison time the pair could face if convicted at trial. The charges are similar to those filed in October.

Here’s a breakdown of the charges, and a closer look at those who have faced charges throughout Mueller’s so far nearly year-long probe.

Michael Flynn

Michael Flynn, who served as Trump’s national security adviser for less than a month before resigning, was charged and pleaded guilty in December 2017 to making false statements to the FBI. 

Flynn reportedly lied about his talks with Russia’s ambassador to Washington. In late 2016, while former President Barack Obama was still in office, the two allegedly spoke about the U.S. sanctions imposed on Russia.

This raised concerns that Flynn, a retired Army lieutenant general, misled Trump officials about his conversations with Russian officials.

Paul Manafort

The special counsel filed a 32-count indictment on Feb. 22 against former Trump campaign chairman Paul Manafort and aide Rick Gates, accusing the pair of tax evasion and bank fraud. 

The new indictment accuses Manafort and Gates of doctoring documents to inflate the income of their businesses and then using those fraudulent documents to obtain loans. It also accuses Manafort of evading taxes from 2010 through 2014 and, in some of the years, concealing his foreign bank accounts.

And on Feb. 23, a newly unsealed indictment accused Manafort of secretly paying former European politicians to lobby on behalf of Ukraine.

Manafort turned himself in to federal authorities in the fall. The 68-year-old served as Trump’s campaign manager for a few months in 2016. Gates, Manafort’s business associate, also turned himself in at the time. 

Manafort was initially charged in a 12-count indictment in connection with foreign lobbying work, and he pleaded not guilty. The charges included: conspiracy against the U.S., conspiracy to launder money, false statements, unregistered agent of a foreign principal, and multiple counts of failure to file reports of foreign bank and financial accounts, according to a special counsel’s office spokesman.

Manafort sued to have the case against him dismissed and argued that Mueller had overstepped his bounds by charging him for conduct he says is unrelated to Russian interference in the 2016 election.

Richard Gates

Rick Gates was named alongside Manafort in the recent charges brought by the special counsel. He’s accused of 11 counts related to filing false income tax returns and three counts of failure to report foreign bank and financial accounts.

Gates pleaded guilty on Feb. 23 to federal conspiracy and false-statements charges.

In wake of the guilty plea, Mueller moved to drop the 22 bank and tax fraud charges against him. The decision to drop the more expansive charges against Gates could suggest that the former Trump campaign official is cooperating and providing good information to Mueller’s team.

Like Manafort, Gates was initially indicted in October in connection with foreign lobbying work; he pleaded not guilty at the time. His charges were similar to Manafort’s – ranging from conspiracy against the U.S. to conspiracy to launder money.

A superseding criminal complaint says Gates was charged with conspiracy against the United States between 2006 and 2017.

George Papadopoulos

A former foreign policy adviser to Trump’s presidential campaign, George Papadopoulos pleaded guilty in 2017 to making false statements to the FBI regarding “the timing, extent and nature of his relationships and interactions with certain foreign nationals whom he understood to have close connections with senior Russian government officials,” according to court documents.

He also reportedly tried to set up meetings between Russian and Trump campaign officials on various occasions. 

Alex van der Zwaan

Mueller’s team charged Alex van der Zwaan, an attorney who allegedly lied to federal investigators in the Russia probe, in federal court on Feb. 16. He pleaded guilty days later. 

According to charging documents, van der Zwaan was employed by a law firm hired by the Ukraine Ministry of Justice in 2012. He admitted to lying about his interactions with Gates.

The charge against van der Zwaan does not involve election meddling or the Trump campaign’s operations. It stems from the special counsel’s investigation into a covert Washington lobbying campaign Manafort and Gates are accused of directing on behalf of pro-Russian Ukrainian interests.

The law firm where he used to work says it fired him last year and has been cooperating with authorities.

Richard Pinedo

Richard Pinedo, a California man who sold bank accounts to Russians meddling in the election, pleaded guilty to using stolen identities to set up the bank accounts earlier this month.

The U.S. government said Pinedo did not know that he was dealing with Russians when he sold the accounts. The plea was announced on the same day that Mueller’s office charged 13 Russians and the indictment was the most direct allegation to date of illegal Russian meddling during the campaign.

Pinedo ran the online service Auction Essistance, buying and selling bank account numbers so customers could avoid security measures of digital payment companies, Newsweek reported. The Auction Essistance website says it is “currently undergoing scheduled maintenance.”

13 Russian nationals

A grand jury indicted 13 Russian nationals and three Russian companies in February for allegedly interfering in the 2016 election. In the case, Mueller details a sophisticated plot to wage “information warfare” on the U.S.

The indictment is the first to be brought against Russian nationals in Mueller’s investigation. 

However, the Justice Department said the indictment does not allege that the interference changed the outcome of the election.

“There is no allegation in this indictment that any American was a knowing participant in this illegal activity,” said Deputy Attorney General Rod Rosenstein, who oversees the special counsel probe.

Fox News’ Samuel Chamberlain and The Associated Press contributed to this report.