Millionaire pedophile Jeffrey Epstein died in an apparent suicide while in federal custody in Manhattan early Saturday, a stunning end that both infuriated and baffled his victims, and the federal officials responsible for his safety.

For reasons still unclear, the jet-setting 66-year-old financier, who had faced up to 45 years in prison on charges of sex-trafficking dozens of teenage girls — accusers who have also implicated many in his circle of powerful, wealthy pals — had recently been taken off suicide watch, officials said.

He was found unresponsive in his single-inmate cell at the Metropolitan Correctional Center at about 6:30 a.m. and was dead on arrival at nearby NewYork-Presbyterian Lower Manhattan Hospital, sources told The Post.

The disgraced money manager was found hanging by his neck, a source told The Post.

US Attorney General William Barr said he was “appalled” by the apparent suicide at the ultra-secure lockup, which has held some of the world’s worst terrorists and drug lords. Suicides there are nearly unheard of.

“I was appalled to learn that Jeffrey ­Epstein was found dead early this morning from an apparent suicide while in federal custody,” Barr said in a statement.

“Mr. Epstein’s death raises serious questions that must be answered. In addition to the FBI’s investigation, I have consulted with the inspector general, who is opening an investigation into the circumstances of Mr. Epstein’s death,” Barr said.

Upon finding Epstein unresponsive in his cell, jail staff immediately attempted to revive him, officials said.

EMS responded to the hospital after a 6:39 a.m. emergency call, sources told The Post.

Epstein’s body remained at the hospital until Saturday afternoon, when Medical Examiner’s staffers in a black van took it to the ME’s Office downtown.

A second, white medical examiner’s van was parked at a separate door as an apparent decoy for the crowd of press and photographers gathered at the hospital.

“We are enormously sorry to learn of today’s news,” his defense team said in a joint statement. “No one should die in jail.”

Epstein had inexplicably been taken off suicide watch despite an incident three weeks ago when he was found sprawled on the floor of his cell, nearly unconscious, and with injuries to his neck.

Investigators were still probing whether the July 23 incident was a suicide attempt or an assault by a fellow inmate.

He was being housed in the jail’s high-security Special Housing Unit, in which high-profile or dangerous detainees are kept separate from the general population.

Until recently, the jail had housed Mexican drug lord Joaquin “El Chapo” Guzmán, who is now at a supermax prison in Colorado.

At MCC, two jail guards are required to make separate checks on all prisoners every 30 minutes — but overnight, that procedure was not followed, a source told Reuters. Prisoners on suicide watch get checked every 15 minutes.

Former US Attorney Preet Bharara tweeted that he was “dumbfounded” by Epstein’s death.

“There should be — and almost certainly is — video of Epstein’s suicide at MCC,” he said. “One hopes it is complete, conclusive, and secured.”

Epstein’s death comes just a day after a Manhattan federal judge unsealed a trove of shocking and repulsive civil-court depositions by the financier’s former employees, friends and victims.

The new documents, numbering 2,000 pages, portrayed Epstein as an insatiable pervert who demanded a daily diet of three orgasms and who left scores of teenage girls — some as young as 14 — sexually assaulted and emotionally shattered.

One alleged victim, Virginia Giuffre, claimed Epstein forced her to sleep with Britain’s Prince Andrew, Democratic former Sen. George Mitchell of Maine, Democratic New Mexico Gov. Bill Richardson, investment banker Glenn Dubin and late longtime MIT professor Marvin Minsky.

Minsky’s family and the other men have denied her accusations.

The documents also include the transcript of a 2016 deposition in which Epstein repeatedly refused to answer questions in order to avoid incriminating himself.

“Heads must roll,” Nebraska Sen. Ben Sasse, a Republican member of the Senate Judiciary Committee, wrote to Barr in a scathing letter Saturday.

“Every single person in the Justice Department — from your Main Justice headquarters staff all the way to the night-shift jailer — knew that this man was a suicide risk, and that his dark secrets couldn’t be allowed to die with him,” Sasse wrote.

There’s no question Epstein should have been under continual watch, said Cameron Lindsay, a former warden who ran three federal jails and who called the death a “shocking failure.”

“Unequivocally, he should have been on active suicide watch and therefore under direct and constant supervision,” Lindsay said.

“It’s embarrassing,” one federal law-enforcement source told The Post of Epstein.

“This is the highest-profile inmate in that facility, and considering that he may have attempted suicide two weeks ago — how could they let this happen?”

Mayor de Blasio tweeted, “Some of wealthiest people in the world committed a horrible crime. If they think for a second that they got away with it because Jeffrey Epstein is dead, they’re dead WRONG.”

The convicted pedophile had wiggled out of a 53-page 2007 federal indictment on similar sex-trafficking charges from Miami, ultimately pleading guilty to a state charge of soliciting prostitution from a minor.

He was allowed to serve most of his yearlong sentence on work release — during which he allegedly continued to have sex with young women.

But in this latest case, Epstein had been ordered held without bail since his arrest July 6 at Teterboro Airport in New Jersey.

Prosecutors said that between 2002 and 2005, he ran a sex-trafficking ring in which he abused dozens of underage girls in his mansion on East 71st Street in Manhattan and his waterfront compound in Palm Beach, Fla.

His lawyers had repeatedly asked a Manhattan federal judge to let him be released to electronically monitored house arrest.

Epstein had access to a private plane, a Caribbean island estate and a fortune estimated by prosecutors at over $500 million. Prosecutors also said they found a fake passport among his belongings.

His lawyers were still appealing the bail ruling when he died.

Additional reporting by Stephanie Pagones and Khristina Narizhnaya

With Post wires