Ex-Trump aide Paul Manafort's lawyer has told a court his deputy led a "secret life" and told so many lies he could not keep track of them all.
Mr Manafort's defence team was cross-examining his former right-hand man, Rick Gates, who is now star witness for the prosecution.
Gates told the court on Monday that Mr Manafort ordered him to commit fraud.
This is the first criminal trial to come from the Department of Justice-led inquiry into alleged Russian meddling.
Mr Manafort, 69, has pleaded not guilty to bank fraud and tax fraud.
Gates, 46, struck a plea deal with prosecutors in February, admitting two charges of conspiracy and lying to the FBI.
The case arises from the pair's consultancy work for Russian-backed Ukrainian politicians.
Sex, lies and taxes
Mr Manafort's legal team sought to undercut Gates' credibility on Tuesday, day six of the trial.
Defence attorney Kevin Downing asked about the witness's co-operation with special counsel Robert Mueller, who is leading the Russia probe.
"After all the lies you told you expect this jury to believe you?" Mr Downing asked Gates.
"I'm here to tell the truth," the witness replied. "Mr Manafort had the same path. I'm here."
The defence lawyer pointed out Gates had lied to investigators before entering his guilty plea.
"Have they confronted you with so many lies that you can't remember?" Mr Downing added.
The defence lawyer also pressed Gates on his adultery.
"There was another Richard Gates, isn't that right?" Mr Downing asked. "A secret Richard Gates?"
The witness responded that he had had an extramarital affair over 10 years ago.
Gates acknowledged keeping a flat in London for two months during those trysts, and listing luxury hotels as a business expense.
He also said he had possibly submitted personal expenses to President Donald Trump's inaugural committee for his work on the election campaign.
And he conceded he had penned a fraudulent letter to prospective investors for a movie project.
One text exchange drew laughter from the court when a message was read out revealing Mr Manafort's dismay at his high tax rate.
Beginning with an expletive, he wrote: "You told me you were on top of this... This is a disaster."
What's the background?
The two former business partners were indicted last October for hiding millions of dollars they made lobbying for Russian-backed Ukrainian politicians.
The charges relating to the pair's political consulting largely predate the Trump 2016 election campaign they worked on together.
Gates told the Alexandria, Virginia, court on Monday he was helping prosecutors in the hope of leniency.
Gates still faces up to six years in prison under the terms of his plea deal.
He has avoided all eye contact with Mr Manafort in his two days of testimony, according to reporters in court.
'There's tears in your eyes'
Tensions are running high in the courtroom, and not just on the witness stand.
On Monday the judge accused the prosecutor of getting weepy as the pair argued, according to a court transcript.
The dispute began as Judge TS Ellis told Greg Andres his line of questioning was not relevant.
"Look at me when you're talking to me," the judge reprimanded Mr Andres, out of earshot of the jury.
The prosecutor protested that he did not "want to get in trouble for some facial expression".
Judge Ellis said: "There's tears in your eyes right now."
Mr Andres denied it.
"Well, they're watery," Judge Ellis said. "Look, I want you to focus sharply on what you need to prove - to prove the crime.
"And I don't understand what a lot of these questions have to do with it."