Leonardo DiCaprio testifies at trial of Fugees' Pras Michel

Actor Leonardo DiCaprio took the witness stand in federal court in Washington, D.C., on Monday to testify in the trial of hip-hop star Pras Michel on charges Michel ran an illegal multimillion-dollar influence scheme, which he denies.

A founding member of the '90s group the Fugees, Michel is accused of illicitly funneling money from a Malaysian financier into U.S. politics, including by making contributions to former President Barack Obama's 2012 reelection campaign.

Michel has maintained his innocence and at one point rejected a plea agreement offer from the government. His trial began on Thursday.

He declined to comment on DiCaprio's testimony when asked by ABC News on Monday.

DiCaprio, called as a prosecution witness, took the stand in a dark, tailored suit and light-blue shirt with his signature goatee and slicked hair as the courtroom swelled to capacity. He spoke slowly and carefully as he answered questions from the government about his relationship with alleged fugitive Malaysian financier Low Taek Jho, also known as Jho Low.

Michel is charged with conspiring to commit fraud, making illegal campaign contributions and falsifying records, among other counts. Prosecutors appeared to use DiCaprio's testimony to show the jury how Low allegedly leveraged money to gain access to powerful and wealthy people, including celebrities.

DiCaprio is not accused of criminal wrongdoing.

His testimony featured some lighter moments: At one point he was asked about details from a party with Low in Las Vegas and admitted he couldn't quite recall, eliciting some laughter from the courtroom audience.

He said Low invited him to attend several parties and events after the two first met in Las Vegas over a decade ago.

"He would have a multitude of lavish parties," DiCaprio said.

Low had been inquiring about projects DiCaprio was interested in pursuing when DiCaprio broached the idea of financing his movie "The Wolf of Wall Street," the actor testified. At the time, DiCaprio said he only knew of Low as an "incredibly successful" businessman.

After DiCaprio and the studio conducted background checks, DiCaprio said, his representatives gave the "green light" to proceed with Low financing the film through his production company, Red Granite Pictures.

At one point, DiCaprio described a discussion with Low about politics in which he said the financier discussed making a "significant donation" to the Democratic Party of about "$20 to $30 million."

"I said, 'Wow, that's a lot of money,'" DiCaprio recalled.

The defense questioned DiCaprio directly about potential problems with the foreign financing of "The Wolf of Wall Street." DiCaprio said he was aware of "complications" with the money but that he was never asked to give any of it back.

Other potential witnesses in the trial could include former Trump White House chief of staff John Kelly, former Trump national security adviser H.R. McMaster and casino mogul Steve Wynn, according to court documents.

After DiCaprio stepped down from the stand on Monday, the court began hearing from a former congressional candidate, Rudolph Moise, who testified to taking money from Michel before realizing the potential criminal liabilities.