WASHINGTON (Reuters) - Paul Manafort, a businessman and longtime Republican Party operative, surrendered on Monday to the Federal Bureau of Investigation to face the first charges produced by a special counsel investigation into alleged Russian meddling in the 2016 U.S. presidential election.

Federal agents arrive with former Trump campaign manager Paul Manafort (back seat) in custody on charges related to special counsel Robert Mueller's investigation into alleged Russian meddling in the 2016 U.S. presidential election, at the federal courthouse in Washington, U.S., October 30, 2017. REUTERS/Jonathan Ernst

Manafort and his associate Rick Gates were indicted by a federal grand jury. The 12-count indictment included conspiracy against the United States, conspiracy to launder money, being an unregistered agent of a foreign principal, making false and misleading statements and seven counts of failure to file reports of foreign banks and financial accounts.

Both pleaded not guilty to the charges.

The Kremlin has denied it meddled in the election campaign to try to tilt the vote in Trump’s favor. Trump has denied any collusion by his campaign.

Who is Paul Manafort?

Manafort is a veteran Republican operative who has worked as a Washington lobbyist and international political consultant. His former clients include authoritarian leaders such as the late Ferdinand Marcos of the Philippines and Russian and Ukrainian businessmen and politicians. Manafort was a campaign manager for the Trump campaign in the summer of 2016.

What does the indictment charge they did?

The indictment against Manafort and Gates says they both generated tens of millions of dollars of income from Ukraine work and laundered money through scores of U.S. and foreign entities to hide payments from U.S. authorities between 2006 and through at least 2016.

In June, Manafort and Gates retroactively registered with the Justice Department as foreign agents, in a Foreign Agents Registration Act filing that showed they earned $17.1 million for lobbying on behalf of the Party of Regions, a pro-Russian political party in Ukraine, between 2012 and 2014.

The indictment said they concealed from the United States their work and revenue as agents of Ukrainian political parties. They used their wealth to lead a “lavish lifestyle” without paying taxes on the income, prosecutors said. The indictment says that more than $75 million flowed through Manafort’s and Gates’ offshore accounts. Manafort, the indictment said, laundered more than $18 million.

The indictment also alleges Manafort and Gates, along with others, conspired to defraud the United States by “impeding, impairing, obstructing, and defeating the lawful governmental functions” of the Department of Justice and the Treasury Department between 2006 and 2017.

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Manafort was indicted on nine counts and Gates was indicted on eight counts.

What are Manafort’s links to Trump?

Manafort joined the Trump presidential campaign in March 2016 and later became campaign manager, but he was forced to resign in August as questions emerged about his previous work for the political party of the Kremlin-backed former Ukrainian president, Viktor Yanukovich.

Business Insider reported that Manafort and Trump have been connected since the 1980s, when Trump hired Manafort’s lobbying firm to help the Trump Organization.

In 2006, Manafort and his wife bought an apartment in Trump Tower in New York, which Manafort still owns and where he lives when he is in Manhattan, Business Insider reported.

How do the charges relate to Trump?

“It has nothing to do with the campaign or the allegations of collusion with Russia,” said Washington attorney John Dowd, who represents Trump in the Russia probe.

A Trump confidante said: “As it relates to the president, this is nothing. All of the 12 counts of the indictment that came down today, all of it predates their tenure at the campaign.”

The special counsel’s indictment says Manafort and Gates laundered the money through “scores of United States and foreign corporations, partnerships and bank accounts” from approximately 2006 through “at least 2016.”

Who is Rick Gates?

Rick Gates was Manafort’s deputy and business associate. According to two former high-level Trump staffers, Gates essentially functioned as the Trump campaign manager for more than two months, all while not collecting a paycheck.

The New York Times reported in June that the Trump transition team had been ordered to preserve materials related to ongoing investigations into alleged Russian meddling in the 2016 election. According to the Times, the memo from the special counsel’s office to the former transition team also sought specific information on five people including Manafort and Gates.

According to the indictment, between at least 2006 and 2015 Manafort and Gates acted as unregistered agents of the Ukrainian government, a Ukrainian political party that was headed by Ukraine’s then president, Yanukovich, and Yanukovich himself. The indictment said they both generated tens of millions of dollars in income as a result of their Ukraine work.

Yanukovich has been living in exile in Russia since he was ousted by mass street protests in Kiev in 2014. His departure lit the fuse for Moscow’s annexation of Crimea and a separatist uprising in mainly Russian-speaking eastern Ukraine.

The indictment said Gates aided Manafort in obtaining money from offshore accounts and that Gates used that money to pay for personal expenses including “his mortgage, children’s tuition, and interior decorating of his Virginia residence.”

How significant is Gates’ arrest?

The indictment lays out the extent of Gates’ involvement with Manafort going back years. That could potentially open the door for Gates to testify against Manafort and others in the future. David Sklansky, a professor at Stanford Law School and former federal prosecutor, said Gates could feel pressure to cooperate and provide testimony against Trump.