CHICAGO — Federal prosecutors in Chicago have asked for a protective order on all evidence turned over in the sexual abuse case against singer R. Kelly, telling a judge Thursday that putting sensitive material in the public domain would have a “chilling effect” on cooperating witnesses.

In asking for the blanket protective order on discovery, Assistant U.S. Attorney Angel Krull also said the government may seek to supersede the indictment against Kelly and two former associates, possibly adding “additional charges and additional defendants” as the case progresses.

Krull told U.S. District Judge Harry Leinenweber that evidence Kelly and his entourage obstructed justice in his 2008 trial on child pornography charges was particularly sensitive. Some victims have been repeatedly harassed by Kelly’s followers, while other witnesses “have been hesitant to come forward and cooperate with the government,” she said.

“They don’t want their names out there,” Krull said. “They don’t want to be hounded by the press (or) fans of Mr. Kelly. … One witness had to quit her job (because of the harassment).”

Lawyers for Kelly and his two co-defendants — former manager Derrel McDavid and ex-employee Milton “June” Brown — objected to the ban on releasing certain materials, arguing that much of the evidence has already come out through media reports and in civil lawsuits filed by alleged victims.

Kelly’s lead attorney, Steven Greenberg, also noted that an attorney for some of the alleged victims has been holding news conferences discussing evidence in the case despite being under federal indictment himself for fraud. Greenberg did not name the attorney, but it was a clear reference to Michael Avenatti, who became nationally known for his outspoken representation of adult film star Stormy Daniels.

Leinenweber said whomever Greenberg was talking about should “be advised” to keep his mouth shut. The judge said he’d rule on the proposed protective order next week.

In a separate issue, the acting U.S. marshal in Chicago, Jason Wojdylo, asked Leinenweber to look further into the possibility of holding an arraignment via teleconference for Kelly on a separate indictment he faces in New York.

Transporting such a high-profile prisoner across the country for what would likely be a very brief, routine hearing would be costly and logistically difficult, Wojdylo said. Greenberg and co-counsel Michael Leonard objected to the idea of a teleconference, saying Kelly had a right to enter his plea in person before the judge who’s going to oversee the case in federal court in Brooklyn.

After a brief sidebar to discuss logistics, Leinenweber ruled that Kelly must be taken to New York for his arraignment there on Aug. 2. The singer will then be returned to Chicago in time for a status hearing here on Sept. 4, the judge said.

The issues underscore the logistical difficulties facing authorities with a celebrity of Kelly’s magnitude being held without bond while facing charges in three separate jurisdictions.

Kelly was charged in four separate indictments earlier this year in Cook County alleging he sexually assaulted one woman and sexually abused three others. All but one was allegedly underage at the time. Wojdylo said Kelly has been in held in isolation at the Metropolitan Correctional Center “for his safety” since his arrest two weeks ago on the federal charges.

Kelly has so far refused offers of a cellmate or to be moved to general population, he said.

Leinenweber also said he’s received emails and other correspondence from “people that like Mr. Kelly.” The judge did not elaborate on what the communications said.

The 13-count federal indictment brought in Chicago alleged Kelly and his associates fixed the R&B superstar’s 2008 child pornography trial in Cook County by paying off witnesses and victims to change their stories.

The indictment also alleged Kelly, McDavid and Brown paid hundreds of thousands of dollars to recover child sex tapes before they fell into the hands of prosecutors. All three defendants have pleaded not guilty.

The 18-page New York indictment against Kelly alone accused the singer of racketeering conspiracy, alleging Kelly identified underage girls attending his concerts and grooming them for later sexual abuse. More defendants in R Kelly’s case.