Paul Manafort, who ran Donald Trump’s presidential campaign, surrendered to federal authorities on Monday, hours after authorities summoned him and his former business associate Rick Gates.

Manafort was indicted on charges of money laundering and conspiracy against the United States, Reuters reported. Gates is yet to surrender.

These are the first charges to be filed in the investigation into alleged Russian meddling in the 2016 US elections. Special Counsel Robert Mueller, a former director of the Federal Bureau of Investigation, has been investigating alleged financial dealings between Trump’s aides and foreign governments, including Russia and Turkey, for possible money laundering and tax evasion.

Monday’s charges do not relate to Trump’s campaign, but to the two men’s Ukrainian business dealings up to 2015, BBC reported.

According to records seen by the The New York Times, Gates’ name appears on documents connected with companies that Manafort’s firm set up in Cyprus. These firms were set up to receive payments from politicians and entrepreneurs in Eastern Europe, the report said.

On Sunday, Trump went on a tirade on Twitter, after the first charges in the investigation were filed two day earlier. Trump said the allegations of a collusion between his campaign and Russia were part of a “witch hunt for evil politics”. The president claimed investigators had not thoroughly examined allegations against Hillary Clinton or the 2010 Uranium One deal with Russia, which was approved by the Barack Obama administration.

“All of this ‘Russia’ talk right when the Republicans are making their big push for historic Tax Cuts & Reform. Is this coincidental? NOT!” Trump said.