Kid Cudi, the rapper whose brief relationship with Casandra Ventura is said to have led to angry threats by Sean Combs, is expected to take the witness stand on Thursday in the music mogul’s sex-trafficking and racketeering trial.

The rapper, whose real name is Scott Mescudi, is part of an important narrative at the heart of the racketeering conspiracy charge against Mr. Combs. The government has accused Mr. Combs of running a criminal enterprise for two decades and said his associates set fire to a rival’s car by slicing open the convertible top and dropping in a Molotov cocktail.

In 2023, after Ms. Ventura filed the lawsuit that kicked off Mr. Combs’s legal troubles, Mr. Mescudi confirmed that his car had exploded. But he has yet to speak publicly about the details of his role in the case.

Mr. Combs has pleaded not guilty to all charges against him, and his lawyers have said he was “simply not involved” in the allegations of arson put forward by prosecutors.

While on the witness stand last week, Ms. Ventura, the singer known as Cassie, recalled the chaotic aftermath once Mr. Combs learned about her budding relationship with Mr. Mescudi in late 2011. She said Mr. Combs made the discovery while looking through her phone at the site of a “freak-off,” the sex marathons with male prostitutes at the center of the case.

Ms. Ventura testified that Mr. Combs lunged at her with a wine bottle opener and, later that day, threatened to release sexually explicit videos of her in retaliation.