For years, anyone who wanted access to Sean Combs had to go through Kristina Khorram first.

An employee at his company since 2013, becoming his chief of staff in 2020, Ms. Khorram was the mogul’s “right hand,” as he once called her. Before leaving her role in the last year, she commanded a rotating army of personal assistants for Mr. Combs and was the central go-between for his multifaceted business empire.

While much of her work related to Mr. Combs’s businesses, she also made doctor’s appointments for his girlfriends. Made sure their rent was paid. Apprised them of the boss’s daily moods.

“Don’t know how I’d function without her,” Mr. Combs wrote in a Facebook shout-out in 2021.

The actions of Ms. Khorram and others who worked for Mr. Combs over the years are now being scrutinized in federal court, where prosecutors are trying to convince jurors that Mr. Combs is guilty of sex trafficking and racketeering conspiracy, asserting that he ran a “criminal enterprise.”

Ms. Khorram, 38, has not been charged in the case, has not been called as a witness and has denied wrongdoing in the past. But her presence is woven through various accounts given at the trial of wrangling hotel logistics for the sex marathons that are at the heart of the case, or of arranging for drugs to be transported by plane to the music mogul.

“Her duties as Mr. Combs’s chief of staff were extremely broad,” Meredith Foster, a prosecutor, told the judge this month. “They involved setting up hotel nights,” she added, “facilitating the transportation of narcotics, various items such as that.”

During the trial, prosecutors have described the behavior of various bodyguards and staff at Mr. Combs’s companies, as well as Ms. Khorram, as they argue to the jury that the conduct of the employees was not just the work of dutiful assistants, but of racketeering co-conspirators.