But while the trial has only vaguely touched on the Trump campaign directly, and the core allegations of the indictment don't have much of anything to do with Trump, the trial has raised a key unanswered question about why Manafort agreed to join the Trump campaign for free. He also is accused of fraudulently obtaining millions more in bank loans, including while he was working on the Trump campaign.
Gates, who pleaded guilty to charges in February and is cooperating on the possibility of a reduced sentence, has testified that he helped Manafort falsify his tax returns, lie to banks to get loans and hide foreign bank accounts.
The questioning of Paul Manafort's protege during the political consultant's financial fraud trial has turned confrontational and personal, focusing on Rick Gates' own crimes as well as an extramarital affair and a plea agreement.
Manafort couldn't have followed his income "that closely" since Gates had "stolen" hundreds of thousands of dollars from him, Ellis said. They have tried several times to impugn his credibility before the jury. They also need to prove he did so with intent and not by mistake.
Gates laying out a roadmap on how he and Manafort allegedly dodged USA taxes. after admitting Monday they committed numerous crimes as business partners. Gates said the money he took was sent to his account in the United Kingdom and was never disclosed to his accountants or the US government.
While Gates' offered a firsthand account of a co-conspirator, prosecutors have largely sought to make their case through documentary evidence to demonstrate Manafort controlled offshore bank accounts containing millions of dollars.
Gates's testimony wrapped moment later.
Both Manafort and Gates were indicted previous year on charges of bank and tax fraud as part of Special Counsel Robert Mueller's probe.
Prosecutor Greg Andres asked Gates Thursday whether Mueller's team had told him how to answer questions. But Trump has shown interest in the proceedings, tweeting support for Manafort and suggesting he has been treated worse than gangster Al Capone.
The 46-year-old, who has pleaded guilty to conspiracy and is cooperating with the government, began the day by describing how he helped Manafort evade USA taxes on millions of dollars earned from political consulting work they did in Ukraine.
Paul Manafort was concerned after a 2014 Federal Bureau of Investigation interview that one of the companies used to pay the former Trump campaign chairman for his Ukrainian political consulting work wasn't "clean". Manafort has pleaded not guilty to the charges. Prosecutors had previously said that Manafort's interactions with Calk were the only part of the trial expected to overlap with his Trump campaign role.
The testimony, stretching across three days, created an extraordinary courtroom showdown between the two former Trump campaign aides who were indicted together. Courtroom illustration courtesy of Bill Hennessy.
Melinda James, a mortgage loan assistant at Citizen's Bank, testified about a loan application from Manafort she helped process in late 2016 and early 2016.
Emphasizing Gates's infidelity is a part of the defense's attempt to puncture his credibility and call into question the crimes he's accusing Manafort of committing.
At the time he worked for Trump, jurors heard, Manafort's business in Ukraine had always been dried up, and his firm didn't have any clients.
He showed jurors how the Federal Bureau of Investigation had painstakingly traced wire transfers from foreign bank accounts to retailers in the United States who sold Manafort expensive goods - including the custom men's clothier Alan Couture, where Manafort bought jackets made of ostrich and python skin that each cost five figures.
"WTF", Mr Manafort wrote in response, "How could I be blindsided like this".