A former girlfriend of Sean Combs is set to retake the stand on Monday at his federal trial to continue her testimony about a series of sex marathons with male prostitutes, which she said she felt pressured to continue because Mr. Combs was funding her livelihood.

As the trial enters its fifth week, prosecutors are expected to drill down on a key part of their sex-trafficking case: allegations of financial coercion.

The former girlfriend, who is known in court by the pseudonym Jane, spent more than seven hours last week testifying about her tumultuous relationship with the music mogul, which started in 2021 and continued until his arrest in 2024. Mr. Combs has pleaded not guilty to the charges of sex trafficking and racketeering conspiracy, and his lawyers have denied that the sex at the center of the case was ever coercive.

Jane testified last week that in an effort to fulfill her boyfriend’s fantasies, she began to participate in drug-fueled sexual encounters with a succession of hired men that the couple called “debauchery” or “hotel nights.” Her account of the sex marathons — which could last for days and typically involved Mr. Combs watching and masturbating — aligned with the “freak-offs” described by Casandra Ventura, another former girlfriend who testified at the start of the case.