(CNN)Rick Gates' fate has long been tied to the fortunes of Paul Manafort.
Gates and Manafort, longtime business associates who served together on the Trump campaign, were the first two officials indicted Monday in connection with Justice Department special counsel Robert Mueller's investigation, on 12 counts that included conspiracy against the United States, conspiracy to launder money and unregistered agent of a foreign principal.
The charges do not cover any activities related to the campaign, though it's possible Mueller could add additional charges.
Manafort served as Trump campaign chairman, and he ran the Trump campaign for several months with Gates serving as his deputy. Gates stayed on the campaign after Manafort was ousted amid questions about his work in Ukraine. But Gates was ousted from a pro-Trump advocacy group earlier this year amid mounting questions about Manafort.
The pair's relationship goes back years. Gates joined Manafort's lobbying firm in the mid-2000s when he handled projects in Eastern Europe, including in Ukraine.
Gates has denied any wrongdoing. "Everything was done legally and with the approval of our lawyers," Gates said in a June interview with The New York Times. "Nothing to my knowledge was ever done inappropriately."
Business in Ukraine
The charges against Gates are tied to his lobbying work with Manafort's firm.
When Gates joined Manafort's lobbying firm in the mid-2000s, they worked for the former president, Viktor Yanukovych and his pro-Russia Party of Regions.
Manafort's firm first came under scrutiny from US investigators in 2014, when they sought to determine whether his and other Washington-based lobbying firms failed to register as foreign agents for the Yanukovych regime.
Yanukovych was ousted amid street protests in 2014, and his pro-Russian Party of Regions was accused of corruption and laundering millions of dollars out of Ukraine. The FBI sought to learn whether those who worked for Yanukovych — Manafort's firm, as well as Washington lobbying firms Mercury LLC and the Podesta Group — played a role. The Podesta Group is headed by Tony Podesta, the brother of John Podesta, a former chief of staff of the Clinton White House, a senior adviser to President Barack Obama and Hillary Clinton's campaign chairman.
Mueller's team has subpoenaed global banks for account details and transaction records for Gates, Manafort and their other business partners, Bloomberg reported in August.
This summer, Gates and Manafort filed with the Justice Department to register as foreign agents for their work in Ukraine between 2012 and 2014, which earned their consulting company $17 million.
Dealings with a Russian oligarch
Later, Gates was involved with a failed business venture with Manafort and Russian oligarch Oleg Deripaska, who is a close ally of Russian President Vladimir Putin, according to legal filings. The plan was for Deripaska to invest $100 million in a private equity company that Manafort and Gates would manage.
The project fell apart, and Deripaska sued Manafort and Gates in the Cayman Islands for mishandling his money.
During the Trump campaign, Manafort had offered Deripaska a private briefing on the campaign two weeks before Trump accepted the nomination, The Washington Post reported.
Deripaska, a Russian citizen, has offered to cooperate with Capitol Hill investigations in exchange for immunity.
Gates' campaign role
Manafort joined the Trump campaign in late March 2016 and brought Gates on board shortly thereafter.
As Manafort rose in the ranks, so did Gates, who took on a more prominent role after campaign manager Corey Lewandowski was fired in June.
But his stock once again rose and fell with his business partner -- after Manafort resigned in August 2016 amid questions about his Ukraine dealings, Gates' role was diminished, and he later left the campaign.
Questions about Gates' work in Ukraine continued to dog him even after Trump was inaugurated.
Gates was a founding member of America First Policies, a pro-Trump advocacy group, but stepped down after about two months.
Gates was forced to leave amid another round of blistering headlines about Manafort, his longtime business partner and political ally, CNN reported at the time.
Gates has denied any allegations of collusion between the Trump campaign and Russia, telling the Times in June that they were "totally ridiculous and without merit."