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 presidential election campaign.
FBI agents arrested Mr Stone in a pre-dawn raid on Friday.
Hillary Clinton’s 2016 campaign chairman John Podesta, who was targeted in the email hack, accused Mr Stone of knowing about it beforehand.
According to investigators, Mr Stone said he had “communicated” with WikiLeaks founder Julian Assange before the emails’ release and had described the contact as “perfectly legal”.
The indictment accuses the lobbyist of lying to the House Intelligence Committee about what passed between him and WikiLeaks, and of falsely claiming not to have records of it.
Mr Stone is said to have spoken to senior Trump campaign officials – who are not identified – about “organization 1” [believed to be WikiLeaks] “and information it might have had that would be damaging to the Clinton Campaign”.
Prosecutors say Mr Stone was also “contacted by senior Trump campaign officials to inquire about future releases” by WikiLeaks.