WASHINGTON – A federal grand jury has charged President Trump's former campaign chairman Paul Manafort and his business and campaign associate Rick Gates, with 12 counts – including conspiracy, money laundering, failing to register as foreign agents, and making false statements.

The case was unsealed Monday after the defendants surrendered to the FBI.

Manafort and Gates are the first to be charged in a special counsel's investigation and are expected to appear in a federal court on Monday morning. Many of the charges were based on activities that largely took place before their work on Trump's campaign.

Manafort Gates Indictment Filed and Redacted

Special counsel Robert Mueller has been investigating Manafort, who resigned as Trump’s campaign chairman in August 2016, for his financial ties to a pro-Russia party in Ukraine. The FBI searched Manafort’s Virginia home in a pre-dawn raid in July.

Federal prosecutors alleged in court documents that Manafort and Gates sought to hide millions of dollars in payments from Ukraine and its political leaders during the past decade. The money, according to court documents, was "laundered through scores" of foreign corporate entities and bank accounts.

When U.S. authorities made inquiries about the payments last year, Manafort and Gates responded "with a series of false and misleading statements."

Gates had worked with Manafort in the private sector and followed him to Trump's campaign in 2016. Gates wound up moving to the Republican National Committee when Manafort was ousted from the campaign, and he helped set up a pro-Trump super PAC after the election.