On Monday, another witness for the prosecution-former Manafort accountant Cynthia Laporta-testified that in 2006, Manafort received a $10 million loan from Russian oligarch Oleg V. Deripaska, who had close ties to Russian President Vladimir Putin.
Mueller's team hopes Gates' testimony will lead to the conviction of Manafort for a list of financial charges conducted long before he joined the Trump campaign. The current federal trial in the Eastern District of Virginia is based on alleged tax and bank fraud, while next month's Washington, D.C. trial deals with allegations of conspiracy, money laundering, and acting as an unregistered foreign agent.
Prosecutors first presented an email in which Manafort told Gates that he would claim his home in the SoHo neighborhood of Manhattan as a second residence (even though it was a rental property) when applying for a loan at Citizens' Bank.
"Did you commit crimes with Mr. Manafort?" asked the prosecutor.
The defendant's lawyers say Rick Gates embezzled millions of dollars from Mr Manafort's consulting firm.
Jurors will hear again Monday from Cynthia Laporta, an accountant who testified August 3 about going along with phony, backdated documents meant to help lower Manafort's tax bills and secure real-estate loans even as his personal debt rose.
Those admissions are likely to become a focal point for Manafort's defence team when he is cross examined on Tuesday.
Gates said he repeatedly lied to hide the bank accounts and, at Manafort's direction, would classify money that came in as either a loan or income to reduce Manafort's tax burden.More news: Russian Airline Says 18 killed in Siberian Helicopter Crash
While the case has nothing to do with either man's work on the Trump campaign and the charges mostly pre-date that time, the United States president has shown interest in proceedings. His case is the first to go to trial arising from Special Counsel Robert Mueller's investigation into Russian interference in the 2016 US election.
Russia If You're ListeningPaul Manafort: The dictator's fixerIn four years Paul Manafort went from making millions of dollars in Ukraine, to running the Trump campaign, to jail. Gates also worked for the Trump election campaign.
Rick Gates will continue his testimony today.
Laporta detailed multiple examples in which Manafort and Gates sought to doctor financial records, first in order to lower Manafort's taxable income and then later to inflate his income so that he could get bank loans.
Some of the manoeuvrers were at the request of Mr Gates, while others implicated Mr Manafort, Ms Laporta testified.
Gates is the prosecution's star witness after he cut a plea deal this year and admitted two felony charges.
Some of the maneuvers were at the request of Gates, while others implicated Manafort, Laporta testified. One accounting trick saved Manafort $500,000 in taxes, she said.
Prosecutor Greg Andres pointed out that he had created a "loan forgiveness letter between Mr. Manafort and Mr. Manafort". But while Laporta acknowledged that she regularly communicated with Gates, she said she believed Manafort was in the know.