Leonardo DiCaprio gave evidence for the prosecution during the trial against rapper Pras Michel in Washington, D.C. on Monday.
Prakazrel 'Pras' Michel, a founding member of The Fugees, is accused of funnelling money from fugitive Malaysian financier Jho Low, real name Low Taek Jho, to former President Barack Obama's 2012 re-election campaign. He denies a slew of charges, including conspiracy and witness tampering.
DiCaprio appeared in court to testify about his connection to Low, who is accused of spearheading a money laundering and bribery scheme that took billions from the Malaysian state investment fund 1MDB. Low was one of the primary financiers of his 2013 movie The Wolf of Wall Street.
The Oscar-winning actor revealed he had known Michel since the '90s, having met him backstage after a Fugees concert, and had befriended Low at a party in Las Vegas in 2010.
"I understood him to be a huge businessman with many different connections in Abu Dhabi and Malaysia," DiCaprio said, reports The Associated Press.
Low subsequently became a regular donor to the Leonardo DiCaprio Foundation and suggested funding the movie. The 48-year-old insisted he and his team thoroughly reviewed both Low's funding and legitimacy before engaging in any business with him.
"I was given the green light by my team as well as my studio," he stated. "He was a legitimate business person wanting to invest in the movie."
The Titanic star also recalled a "casual conversation" he had with Low concerning funds Low intended to donate to Obama's re-election campaign.
"It was a significant sum - something to the tune of $20-30 million," DiCaprio recounted. "I said, 'Wow that's a lot of money!'"
Prosecutors allege Michel served as a link for Low's stolen millions and his attempts to influence the U.S. government.
Between June and November 2012, Low allegedly transferred over $21.6 million (£15.7 million) to Michel's accounts, which was utilised to channel money into the election campaign. Michel supposedly paid around 20 straw donors to make donations in their name and cover up where the money came from.