Roger Stone, a longtime Trump ally and occasional campaign adviser, became a central figure in the Mueller probe over his extended contacts with Russian hacker Guccifer 2.0, and WikiLeaks, the self-styled transparency group accused of disseminating hacked emails to interfere in the 2016 election.
Stone was arrested and charged with one count of obstruction of justice, five counts of making false statements to Congress, and one count of witness-tampering in January and plans to plead not guilty.
Stone sent out several tweets in the summer of 2016 that raised questions about whether he had prior knowledge about WikiLeaks' plans to publish the hacked emails.
After The Washington Post reported that the Democratic National Committee was hacked by Russian operatives, Stone responded by writing in Breitbart in July 2016 claiming that Guccifer, "a lone hacker," and not the Russian government carried out the hacking.
In the weeks that followed, Stone and Guccifer exchanged several messages on Twitter in which Guccifer expressed admiration for Stone and offered to assist the Trump campaign.
US intelligence officials had long suspected that Guccifer was either a real person linked to Russian intelligence or a fake persona they had created. In March 2018, that suspicion was confirmed when Guccifer accidentally revealed himself to be Russian security officer.
In July 2018, the Russian intelligence officers who had created the Guccifer profile were charged by the special counsel for conspiracy against the United States, aggravated identity theft, and money laundering in relation to the hacks of the DNC, the Democratic Congressional Campaign Committee, and the Clinton campaign.