Manhattan’s top federal prosecutor is calling for an outside authority to take control of New York City’s troubled jails, a major shift that could help persuade a judge to strip Mayor Eric Adams of his power over Rikers Island.

The federal prosecutor, Damian Williams, said in a statement on Monday that Rikers has been in a crisis for years — “a collective failure with deep roots, spanning multiple mayoral administrations” and correction commissioners.

“But after eight years of trying every tool in the tool kit,” Mr. Williams said, “we cannot wait any longer for substantial progress to materialize. That is why my office will seek a court-appointed receiver to address the conditions on Rikers Island.”

Though lawyers for people held in city jails have consistently called for an outside authority — known as a receiver — to take over, Mr. Williams’s statement could provide a powerful push toward making the move a reality.

Mr. Williams’s office said it would also seek to have the city held in contempt of court “to address the ongoing risk of harm” to detainees and jails staff.

Ultimately it will fall to a judge, Laura Taylor Swain, to decide whether a takeover is necessary. The mayor has insisted that change must come from within. Any finding from the judge that the city is unable to manage its own jails could be deeply embarrassing to Mr. Adams and his administration.

In a statement, a spokesman for City Hall said that in the past six months the Department had reduced slashings and stabbings, assaults on staff and injuries to people in custody, among other encouraging statistics.

“Just three months ago, the federal monitor stated that ‘real change has occurred’ on Rikers Island,” the statement said, referring to a court-appointed monitor who oversees the jails. “So, what’s changed?”

The city’s jails, most of which are on Rikers Island in the East River, have been plagued by problems for decades, but the most recent tumult arrived with the onset of the pandemic in March 2020. Covid-19 hit the correction officers who work inside the jails hard and led to mass absenteeism: At the height of the crisis that followed, up to 2,000 officers were failing to show up for work each day.

The jails descended into chaos, with violence and self-harm among detainees skyrocketing in 2021. The following year, Mayor Adams assumed office and appointed a new jails commissioner, Louis A. Molina, who vowed to get things under control. Still, 19 people died while being held in city jails in 2022, or directly after they were released, the most in nearly a decade. Six more have died this year.

In April 2022, Mr. Williams, the U.S. attorney for the Southern District of New York, raised the prospect of an outside authority to run the jails, saying in a letter filed with Judge Swain that they “are in a state of crisis, inmates and staff are being seriously injured, and action is desperately needed now.”

At the time, Mr. Williams said his office was very concerned about whether the city and correction department had “the ability, expertise and will to swiftly make the changes necessary to bring true reform to this deeply troubled agency.”

Mr. Williams’s office said then that absent such a commitment to change, “we will be left with no other option but to seek more aggressive relief, which could involve seeking the appointment of a receiver with independent authority to implement sweeping reforms.”

The prosecutor’s statement on Monday comes amid continuing mayhem at the jails — where three people have died this month alone — as well as reports from a federal monitor who oversees them that accused city officials of hiding important information about troubling episodes of violence and neglect.

With Mr. Williams’s comments, every entity involved in deciding the future of the jails — lawyers for detainees, the federal monitor, Steve J. Martin, and now, the U.S. attorney’s office — save for the city itself has either called for an outside authority to take over, or simply expressed lack of faith in the ability of the administration to turn things around.

In a hearing last month, Judge Swain, of Federal District Court in Manhattan, echoed those complaints, saying that her faith in the city’s leadership had been shaken and signaling she might be open to the possibility of appointing a receiver. The judge has scheduled a hearing for Aug. 10 where lawyers for detainees and Mr. Williams’s office are expected to express their formal recommendations for receivership.

But their support alone would not be enough for an outside authority to take control. Judge Swain would have to find that there were not less extreme alternatives that would solve the issues, and that the city had refused to comply with court orders.

Mr. Martin filed a report earlier this month in which he did not explicitly call for an outside authority to take control. Instead he called for Judge Swain to initiate a court proceeding which could end with New York City being held in contempt for its actions — and to take whatever other corrective action she might think necessary.

The legal case involving Rikers, a compound of eight city jails that house more than 6,000 inmates, has been before Judge Swain since the Legal Aid Society and two private law firms in 2012 filed a class-action lawsuit against the city, then led by Mayor Michael R. Bloomberg, over what it called “a deeply entrenched” pattern of brutality in the city jails.

A spokesman for the Legal Aid Society said he applauded the announcement. “Too many lives have been lost and damaged due to the city’s inability to manage the jails humanely,” he said in a written statement.

In 2014, the U.S. attorney’s office, then led by Preet Bharara, announced that, after a two-and-a-half-year investigation, it had found systematic civil rights violations of male teenagers by guards at Rikers. The prosecutor’s office eventually joined the pending class-action lawsuit.

In June 2015, the administration of Mayor Bill de Blasio reached a wide-ranging settlement in the lawsuit, committing to far-reaching reforms, including the appointment of a monitor, and new policies to restrict the use of force by guards against inmates.

In the meantime, crime fell, leading to reduced crowding at Rikers Island, which in April 2020, reached a population under 4,000 for the first time since 1946. When crime began to surge that summer, the pattern quickly reversed.

Mr. Williams, the U.S. attorney since his appointment by President Biden in 2021, has said Rikers was a major issue for him when he took office, the first topic he asked to be briefed on.

“The problems at Rikers run deep, and they’re decades in the making,” he said in an interview published in April. “They’re very complex. And we understand that. So we’re cleareyed about it, ultimately. But yes, it’s something that is an urgent priority for us.”

By law, the jails on Rikers Island must close by 2027, and the city plans to replace the complex with four smaller lockups based in every borough except for Staten Island. But Mayor Adams has cast doubt upon the plan — the new jails are expected to hold only about 3,300 beds — and he has said he thinks the city needs a “Plan B.”