Jeffrey Epstein’s jailhouse death has shifted the focus of federal authorities to the accomplices who helped him sexually traffic and abuse underage girls, the nation’s top lawman said Monday.

Attorney General William Barr delivered the stern warning to the late pedophile’s cronies during a speech to the Fraternal Order of Police in New Orleans — saying, “Any co-conspirators should not rest easy.”

Barr did not name any suspects, but the feds’ list is most likely headed by Ghislaine Maxwell, 57, who’s been described variously over the years as the late multimillionaire financier’s girlfriend, closest pal and key player in his alleged ­sex trafficking ring.

Court papers unsealed Friday — just hours before Epstein was found “unresponsive” in his cell at the Metropolitan Correction Center in lower Manhattan — also allege that she served as the “madam” in his alleged ring.

The papers, part of a defamation suit that Maxwell settled with Epstein accuser Virginia Giuffre shortly before a scheduled 2017 trial, said that “multiple witnesses” had testified that Maxwell was responsible for “recruiting, maintaining, harboring and trafficking girls for Epstein.”

Even worse for Maxwell, the court papers allege that she was a “‘co-conspirator’ in Epstein’s sexual abuse,” taking “numerous sexually explicit photographs of underage girls involved in sexual activities” and engaging in three-way sex with Epstein and various girls, according to an opinion written by the late Manhattan federal Judge Robert Sweet.

Among the witnesses who testified against Maxwell — the socialite daughter of the late, disgraced British media mogul Robert Maxwell — during pre-trial proceedings was Rinaldo Rizzo, the house manager for her friend, and Epstein’s ex-girlfriend, Eva Dubin.

“Mr. Rizzo testified — through tears — how, while working at Dubin’s house, he observed [Maxwell] bring a 15 year old Swedish girl to Dubin’s house,” Giuffre lawyer Sigrid McCawley wrote in motion ­papers.

“In distress, the 15 year old girl tearfully explained to him that [Maxwell] tried to force her to have sex with Epstein through threats and stealing her passport.”

McCawley also wrote that it was an “undisputed fact” that one of Epstein’s private pilots, David Rodgers, “testified that he flew [Maxwell] and Ms. Giuffre at least 23 times on Epstein’s jet, the ‘Lolita Express’ and that ‘GM’ on the flight log stands for Ghislaine Maxwell.”

Rodgers and another Epstein pilot, Larry Visoski, have cooperated with the federal investigation, The New York Times reported last month.

Another “undisputed fact” that McCawley cited in her motion was testimony by Juan Alessi, the house manager at Epstein’s waterfront mansion in Palm Beach, Fla., that Maxwell was “one of the people who procured some of the over 100 girls he witnessed visit Epstein, and that he had to clean [her] sex toys.”

Maxwell “has not been able to procure a single witness — not one — to testify that [she] did not procure girls for sex with Epstein or participate in the sex,” McCawley wrote.

“Even one of her own witnesses, [former Giuffre fiancé] Tony Figueroa, testified that she both procured girls and participated in the sex.”

Maxwell’s debt-ridden dad, a former member of British Parliament, went missing from his yacht while cruising off the Canary Islands in 1991.

His naked body was found by a Spanish fisherman about 15 miles away, and three pathologists who examined Maxwell differed on the cause of death, blaming it on a heart attack and/or drowning.

Ghislaine Maxwell is believed to be living in London, where she has a historic townhouse in the swank Belgravia section near Hyde Park and a brick country cottage about 90 miles southwest of the city.

She was last photographed in public by The Post, which in January 2015 caught her coming out of an Upper East Side townhouse in which she lived at the time.

The five-story, Beaux Arts mansion at 116 E. 65th St., about nine blocks from Epstein’s townhouse at 9 E. 71st St., was purchased for $5 million in July 2000 by a limited-liability company that was represented by Epstein’s longtime lawyer Darren Indyke.

The property was sold for nearly $15.1 million in April 2016, records show.

Workers in the neighborhood said they often saw Maxwell jogging in the morning and said she would wave while walking her dog, a Hungarian Vizsla, until she abruptly moved out.

“She was very nice lady,” said a parking attendant who works nearby.

“When I read in the newspaper she working as a madam I couldn’t believe it.”

The super at a building on the block also described her as a “very elegant lady, a beautiful woman.”

“Nice dog, too,” he added.

A lawyer for Maxwell did not return a request for comment.

A spokesman for Glenn and Eva Dubin said, “Glenn and Eva Dubin are outraged by the allegations against them in the unsealed court records and categorically reject them.”

Meanwhile, as part of the probe, FBI agents raided several locations, including Epstein’s private island, Little St. James, in the US Virgin Islands on Monday, law enforcement sources told The Post.

The feds were looking for sex toys and other evidence that could corroborate the claims of women who say they were sexually abused by Epstein when they were ­underage.

A team of feds was seen swarming around the Caribbean island in golf carts around 10:30 a.m., NBC News reported, and several were photographed on a thatched-roof dock where a catamaran was tied up against a background of tropical greenery.

Additional reporting by Alex Taylor