WHITE PLAINS, N.Y. -- A judge ordered a federal jail on Wednesday to improve housing conditions for one of Jeffrey Epstein's former cellmates, who wanted to be moved out of the lockup because he feared retaliation by guards.

Nicholas Tartaglione, a former police officer awaiting trial in a quadruple murder case, was sharing a cell with Epstein at the Metropolitan Correctional Center in Manhattan in July when the financier was placed on a suicide watch after being discovered with bruises on his neck.

Several weeks later, Epstein hanged himself in his cell.

Conditions at the Manhattan facility have come under growing scrutiny since Epstein's death, which highlighted chronic staffing shortages. Epstein had been accused of sexually abusing girls and young women and was awaiting trial on federal sex trafficking charges.

The warden of the facility was reassigned and two guards were placed on leave amid allegations that records were falsified to make it appear jail staff had checked on Epstein when they actually failed to do so.

In a court filing, Tartaglione's lawyer called him a "critical witness" in the investigation of the events that led up to Epstein's death.

At a hearing Wednesday before a federal judge in White Plains, New York, defence lawyer Bruce Barket asked the judge to transfer Tartaglione to another jail, saying he'd been threatened and mistreated by jail staff.

He said Tartaglione's requests to shower are "routinely ignored," and that he's been admonished to tell his attorneys to stop speaking publicly about goings-on inside the jail.

"We're not saying put him up at the Four Seasons," he added, requesting Tartaglione be moved to a county jail on Long Island.

U.S District Judge Kenneth Karas said options for transferring Tartaglione are limited because there is only one other federal jail in New York City. The Metropolitan Detention Center in Brooklyn previously held Tartaglione but has declined to house him following a disciplinary issue.

But the judge threatened to hold hearings on conditions at the Metropolitan Correctional Center if officials don't improve Tartaglione's treatment and access to attorneys.

"The status quo really isn't acceptable," Karas said.

Prosecutors said guards have been admonished not to retaliate against Tartaglione. They said they weren't aware of all of Tartaglione's complaints before Wednesday.

Speaking at an event in Dallas, U.S. Attorney General William Barr said that the investigation of Epstein's death is "well along" but has been delayed by some witnesses being unco-operative.

"A number of them required having union representatives and lawyers before we could schedule interviews," Barr said. "However, we're moving expeditiously."

Barr repeated that investigators have found "serious irregularities" at the jail, but said he's seen nothing to undercut a medical examiners' finding that Epstein's took his own life.

Tartaglione's lawyer, Barket, called the jail "the worst facility I've ever experienced," citing a rat infestation and other problems. He said many clients have told him they prefer the conditions in the city-run jail on Rikers Island.

Tartaglione, formerly an officer in Briarcliff Manor, is awaiting trial on charges that he participated in the slayings of four men in a drug deal gone awry. The bodies were found buried on Tartaglione's property.

Meanwhile, a different judge presiding over the federal sex trafficking charges against Epstein invited his accusers and their lawyers to a hearing next week where he'll consider prosecutors' request to dismiss the indictment.

U.S. District Judge Richard Berman said Wednesday he'll conduct a brief hearing Tuesday to consider the dismissal following the financier's suicide Aug. 10.

The judge said he believes the public may have an interest in the legal process surrounding dismissal of charges.

Berman had ordered Epstein held without bail after two accusers urged that he remain behind bars.

The judge said prosecutors and Epstein's lawyers can be heard Tuesday, along with accusers and their lawyers.

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Associated Press Writer Jake Bleiberg contributed to this report from Dallas.