• Ms. McDougal is an ex-Playboy model and, like Ms. Daniels, claimed she had an affair with Mr. Trump.
The case against Donald Trump is focused on a payment made to porn star Stormy Daniels. However, the prosecutor also mentioned another woman.
According to background documents, a payment was made on Mr. Trump's behalf to "Woman 1" - who evidence suggests is Karen McDougal.
Ms. McDougal is an ex-Playboy model and, like Ms. Daniels, claimed she had an affair with Mr. Trump.
She said it lasted 10 months. Mr. Trump has denied it ever happened. Here's what we know about Ms. McDougal and how she's involved in this case.
Born in Gary, Indiana, before moving to Michigan as a child, Ms. McDougal first began modelling in swimwear competitions in her 20s.
She joined Playboy where she went on to win Playmate of the Year in 1998 and was voted "Playmate of the 90s", second to Pamela Anderson.
She later worked as a fitness model, becoming the first woman to appear on the cover of Men's Fitness magazine in 1999. She also appeared in TV adverts and in minor acting roles, such as an uncredited cameo in the 2000 film Charlie's Angels.
In 2006, the New Yorker magazine reported that according to Ms. McDougal, she met Mr. Trump at the Playboy Mansion in Los Angeles, where he was recording an episode of The Apprentice.
She later wrote that Mr. Trump, who was married at the time, "immediately took a liking to me, kept talking to me - telling me how beautiful I was, etc".
Ms. McDougal claims that she and Mr. Trump had a 10-month relationship, and they saw each other "a minimum five times a month". She described the relationship with CNN as loving and consensual.
In 2016, in the run-up to the presidential election, Ms. McDougal signed a deal worth $150,000 (£106,000) to tell her story exclusively to the tabloid newspaper, the National Enquirer.
The agreement banned her from talking publicly about the alleged affair.
However, the article was never published and Ms. McDougal insists she was tricked into silence about the relationship.
Purchasing a story deliberately to then bury it is known as "catch and kill" - and the National Enquirer reportedly did this to suppress negative stories about Mr. Trump.
In 2021, the US Federal Election Commission, which is in charge of enforcing campaign finance law, found that the Enquirer's publisher violated election laws by paying for the rights to Ms. McDougal's story and never publishing it.
It found that the money, which was paid to Ms. McDougal during the 2016 presidential election, amounted to an illegal campaign contribution. The National Enquirer was fined $187,500 (£132,000).
According to her website, Ms. McDougal now describes herself as a model, columnist, advocate, and spokesmodel.
She calls herself an advocate for greater awareness of "breast implant illness", saying her breast implants made her sick. She had them removed in 2017.
In 2018, she publicly apologised to Mr. Trump's wife, Melania, about the alleged affair, saying: "I'm sorry. I wouldn't want it done to me."
"When I look back, at where I was back then, I know it's wrong," she said. "I'm really sorry for that. I know it's a wrong thing to do."
Mr. Trump has always denied having an affair with Ms. McDougal.
The indictment that Mr. Trump is facing is solely targeted toward the hush money payment to Stormy Daniels.
The details concerning Ms. McDougal are contained in the district attorney's statement of facts, which is given as background information to the case.
Mr. Trump has pleaded not guilty to all counts on the indictment.