Paul Manafort, former campaign manager for Donald Trump, arrives at federal court in Washington, D.C., on Friday, June 15, 2018. Aaron P. Bernstein | Bloomberg | Getty Images

The first witness with immunity to testify against President Donald Trump's former campaign chairman Paul Manafort said Friday that she was involved in efforts to file false financial documents. Accountant Cindy LaPorta told a U.S. District Court judge he was "correct" when he asked whether she was testifying under the immunity deal due to concerns that she might be prosecuted. LaPorta was Manafort's accountant in 2014 and 2015 after the retirement of Philip Ayliff, who had testified earlier on Friday. She told prosecutors that she participated in filing a false tax return after Rick Gates, Manafort's longtime business partner, asked the accounting firm to change a loan amount so Manafort's could afford to pay his 2014 income taxes. LaPorta said she knew the loan amount was wrong when preparing Manafort's tax return. "You can't pick and chose what's a loan and what's income," she said. She added: "I very much regret it."

LaPorta, the second accountant of firm Kositza, Wicks & Company to take the stand in Manafort's fraud and conspiracy trial, is one of five witnesses granted so-called "use immunity" in the case. That would bar their testimony from being used against them in a criminal prosecution. Earlier, the lawyers from special counsel Robert Mueller's Russia probe called Ayliff back to the stand after he testified Thursday afternoon that Manafort signed tax forms claiming to have no foreign bank accounts from 2011 to 2014. Manafort, Trump's campaign chairman from May to August 2016, is on trial on 18 counts, including failing to file foreign bank account reports, bank fraud, conspiracy and filing false income tax returns.

Waiting for Rick Gates to testify

LaPorta's testimony compounds the attention Gates is sure to receive as the star witness testifying against Manafort in the trial. Manafort's lawyers sought to establish Gates as the true culprit behind any omissions or mistakes on Manafort's tax filings. "This is about Mr. Manafort placing his trust in the wrong person," defense attorney Thomas Zehnle said in his opening statement. Gates, who was charged along with Manafort in a separate criminal case in Washington, has already pleaded guilty to one count each of lying to investigators and conspiracy against the United States. He agreed to cooperate with the special counsel as part of his plea deal. Ayliff, reading from exhibits presented by prosecutors, said Manafort himself signed letters of engagement with the accounting firm. Ayliff said the letters cautioned that "the law provides various penalties that may be imposed when taxpayers understate their tax liability." Ayliff also told prosecutors his firm asks clients "about foreign accounts every year" — a policy LaPorta confirmed in her testimony, news outlets reported.

A focus on taxes