Political strategist Roger Stone, a long-time ally of President Trump, has been arrested in Florida, charged with seven counts in the Mueller probe.
Mr Stone will appear in court later in the city of Fort Lauderdale.
The indictment includes one count of obstruction of an official proceeding, five counts of false statements, and one count of witness-tampering.
The charges are linked to an alleged Russian-led hack into the emails of Democratic Party officials.
The information contained in the emails was released by WikiLeaks during the 2016 US election campaign.
Mr Stone’s campaign activities have long been under scrutiny by Special Counsel Robert Mueller’s team.
Mr Mueller, a former director of the FBI, is investigating allegations of collusion between Russia and the Trump campaign.
In 2016, US intelligence agencies concluded that Russia had tried to turn the election in Mr Trump’s favour through a state-authorised relay of cyber attacks and fake news stories planted on social media.
Mr Trump has branded the Mueller inquiry a political “witch-hunt”. The Kremlin has always denied meddling in the US election.
So far Mr Mueller’s investigation has led to charges against more than two dozen Russians, as well as several people connected to Mr Trump himself, including his former national security adviser Michael Flynn, and Paul Manafort, the former chairman of his election campaign, who is in jail.
Mr Stone was detained in a pre-dawn arrest.
