Paul Manafort, the former campaign chairman for Donald Trump’s presidential run, surrendered to the FBI Monday morning in response to the bureau’s sprawling Russia investigation.

Special Counsel Robert Mueller is probing Manafort’s windy history advising foreign governments before becoming Trump’s campaign chief from May to August of 2016.

Here’s a rundown on Manafort, why he’s important, and how he ended up in the middle of the Russia investigation:

Manafort is something of a trailblazer in the lucrative business of international political consulting.

Manafort’s most prominent client was Ukrainian President Viktor Yanukovych, who he represented for nearly a decade. Manafort helped rebrand Yanukovych from a Putin puppet to a pro-European Union reformer, which helped him capture the presidency in 2010.

READ: The full indictment charging Paul Manafort with conspiracy against the U.S.

For Manafort’s efforts over nearly a decade, he was paid tens of millions of dollars, which he and his partner Rick Gates — who was also charged on Monday — then laundered through secret offshore bank accounts in Cyprus, Saint Vincent & the Grenadines, and Seychelles, according to the indictment signed by Mueller.

This money allowed Manafort to have a lavish lifestyle in the United States without paying taxes on this income. With that money, the FBI alleges, Manafort bought a condo on Howard Street in SoHo for $2.85 million that he then rented out as an Airbnb. He also purchased a brownstone in Brooklyn, a house in Arlington, Virginia, and an apartment in Trump Tower purchased with cash through an LLC in 2006. The complaint alleges he used these residences as collateral for favorable loans in the U.S.

Yanukovych ultimately backed out of joining the EU and, in response to widespread public protests and violence, fled to Russia.

Manafort’s international consulting dates as far back as the 1980s when he represented the former dictator of the Philippines Ferdinand Marcos, an anti-communist ally of the U.S. who also ran a corrupt and violent government. Amnesty International estimates that his regime killed over 3,000 people and tortured 34,000. He has also represented the military dictator Mobuto Sese Seko of the Democratic Republic of the Congo, and the Angolan guerrilla leader Jonas Savimbi.

Manafort is close with two Trump confidants: businessman Thomas Barrack and longtime Republican political operative Roger Stone.

Manafort was a partner with Stone in the lobbying firm Black, Manafort, Stone, and Kelly. Stone introduced the Manafort and Trump in 1988 at the Republican National Convention. During the presidential campaign, Stone would often lob bombs at Manafort’s internal rival, Corey Lewandowski. Manafort ultimately won that battle and Trump forced out Lewandowski and elevated Manafort in May of 2016.

READ: Paul Manafort indicted in Robert Mueller’s Russia probe

Barrack, a private equity giant, is more directly responsible for Manafort’s hiring. He passed along Manafort’s pitch to Ivanka Trump and Jared Kushner plus personally recommended that Manafort be signed up to run the Republican National Convention in Cleveland, according to a report by the New York Times earlier this year.

“I have managed Presidential campaigns around the world,” Manafort wrote, selling himself to Trump. “I have had no client relationships dealing with Washington since around 2005. I have avoid the political establishment in Washington since 2005.”

Plus, Manafort offered to work for free, something that had great appeal to the famously tight-fisted Trump.

But Manafort did seem intent on cashing in in other ways on the opportunity. The day after Trump named Manafort his campaign strategist, Manafort emailed a Ukraine-based employee of his consulting business and referred to his good press coverage before asking “How do we use to get whole?,” according to reporting by the Washington Post. A Manafort spokesman explained to the Post that Manafort was referring to collect past debts.

Depending on the next steps of the Russia investigation, it may turn out that Manafort was a pretty expensive hire after all.