One woman testified this week that her first flights to see the singer were booked by one of Mr. Kelly’s female assistants, who was aware that she was only 17. Another told jurors that when she was 16, a member of the singer’s entourage approached her at a fast-food restaurant, gave her Mr. Kelly’s phone number and told her he “wants you to call him.”

Prosecutors said in their opening statements that another accuser will testify that she was told she could travel to Mr. Kelly’s studio to interview him for her job in media, but that an employee asked if she needed a condom upon greeting her. And the singer’s associates threatened to expose sexual photos and videos of a fourth woman who had sued him for misconduct if she did not withdraw her claims, the government says.

“I put the number of people who knew about or witnessed that damage in the thousands,” Jim DeRogatis, a music journalist in Chicago who has chronicled the allegations against Mr. Kelly for more than 20 years, wrote in his 2019 book on the subject. “Many knew, and few did anything to stop him.”

The racketeering charge against Mr. Kelly is rarely used in similar criminal cases, though it was employed in the prosecution of the Nxivm sex cult and its leader, Keith Raniere. Experts noted the “criminal enterprise” and enablers at the center of that case were much more defined in structure than in Mr. Kelly’s.

The singer’s defense team has argued that the case — which would need to prove the existence of a criminal enterprise beyond Mr. Kelly — focuses too narrowly on the singer himself. But the final judgment lies with the seven men and five women on the jury, who have heard some of Mr. Kelly’s employees describe how essential they and others were in facilitating the misconduct that the artist is accused of, from the early 1990s through recent years.

One assistant, Anthony Navarro, told jurors he drove female guests to one of the singer’s mansions and, there, was instructed to help maintain a strict set of rules that controlled their daily routines.

And a former tour manager for the singer, Demetrius Smith, told jurors he bribed a government employee for fake identification for the R&B star Aaliyah to marry Mr. Kelly, then 27, who believed that she may have been pregnant with his child. She was 15, and fearing Mr. Kelly’s possible prosecution, his business manager devised a plan for the two to be wed, Mr. Smith said.