Jeffrey Epstein has been pronounced dead after being found unresponsive in his New York City prison cell around 6:30 a.m. Saturday, the New York City Medical Examiner’s Office and Justice Department confirmed. He was 66.

The FBI has opened an investigation into the multimillionaire financier’s “apparent suicide” at the Metropolitan Correctional Center in Manhattan, where he was being held without bail following his July 6 arrest. The Medical Examiner’s office is also investigating his death, a spokeswoman said.

The Justice Department would not confirm to HuffPost whether Epstein had been on suicide watch, but both The Associated Pressand The New York Times, citing unnamed sources, report that he had been taken off suicide watch at some point before his death.

The financier was awaiting trial on charges of sex trafficking underage girls. He had faced a lax sentence in Florida about a decade previously for similar offenses. That case brought to light his ties to wealthy businessmen and politicians including President Donald Trump and former President Bill Clinton.

An incident in which Epstein was found semiconscious in his cell last month with marks on his neck was being investigated as a suicide attempt or possible assault, The New York times reported.

In his decision to keep Epstein behind bars, Judge Richard Berman sided with prosecutors who deemed him to be a danger to the community and an “extraordinary flight risk,” considering that Epstein owned several properties and a private plane.

Epstein pleaded not guilty to charges of sex trafficking underage girls and conspiracy to commit sex trafficking. If convicted, he would have faced up to 45 years in prison. U.S. Attorney General William Barr said in a statement that he was “appalled” to hear of Epstein’s death in federal custody and has asked Inspector General Michael Horowitz to open an investigation into the circumstances. “Mr. Epstein’s death raises serious questions that must be answered,” Barr said. An unnamed accuser represented by attorney Lisa Bloom also expressed her outrage at the turn of events on Saturday. “I’m angry as hell that the prison could have allowed this to happen and that I and his other victims will never see him face the consequences for his horrendous actions,” she said in a statement shared by Bloom. “I hope that whoever allowed this to happen, also faces some kind of consequence. You stole this from us, the huge piece of healing that we needed to move on with our lives.”

Epstein was being held at the Metropolitan Correctional Center, a fortresslike structure in downtown Manhattan that holds 760 men and has been criticized by human rights advocates for its conditions. According to The New York Times, one prisoner who had stayed at both MCC and the notorious Guantanamo Bay prison said Guantanamo was nicer. The facility is used to high-profile suspects: The Mexican drug lord Joaquín “El Chapo” Guzmán was held at MCC for more than two years prior to his July sentencing. It also housed the mastermind behind the 1993 World Trade Center Bombing. A 2016 HuffPost investigation found that suicide is almost entirely preventable behind bars. “People often say, ‘Well, if somebody wants to kill themselves, they’re going to kill themselves,’” Margo Schlanger, a law professor at the University of Michigan who specializes in criminal justice, told HuffPost at the time. “That’s false. If you run a jail with an appropriate degree of suicide prevention, you get almost zero.” Epstein was ordered to register as a sex offender following his 2008 conviction in Florida on an underage prostitution charge. A plea deal reached with then-U.S. Attorney Alexander Acosta that was widely criticized for its leniency required Epstein to spend 13 months at a Palm Beach jail, where he was held in a private wing and permitted to leave for up to 12 hours each day, six days per week on a work permit. A series of articles in The Miami Herald about the controversial deal, which was kept secret from Epstein’s accusers until after it was signed, renewed public outrage over the case of the privileged financier. An attorney for some of his accusers said Epstein was able to continue to abuse young girls during his sentence. Florida state police have opened a criminal investigation into the deal. Acosta, who had been serving as Trump’s labor secretary, resigned after Epstein’s July arrest in New York.

A trove of court documents involving one of Epstein’s accusers, Virginia Roberts Giuffre, was unsealed Friday, containing rafts of allegations against him, his longtime associate Ghislaine Maxwell, and powerful men such as Britain’s Prince Andrew and attorney Alan Dershowitz.

The court records stated that Epstein’s former Palm Beach house manager estimated that, over the years, he had seen a total of 100 young girls visit Epstein under the guise of providing massages.

Two of Epstein’s accusers, Courtney Wild and Annie Farmer, spoke out in New York last month about the trauma they endured.

“I was sexually abused by Jeffrey Epstein at the age of 14,” Wild said in a statement urging Judge Berman to see how Epstein is “a scary person to have walking the streets” prior to his bail hearing.

Farmer became emotional when she told the judge that Epstein had behaved “inappropriately” with her when he flew her at age 16 from New York to New Mexico, where he maintains a ranch linked to the alleged sex trafficking. She said she preferred not to go into more detail.

In July, assistant U.S. Attorney Alex Rossmiller said that dozens of new accusers and witnesses had spoken to authorities since Epstein’s arrest.

A raid of Epstein’s enormous Manhattan townhouse led investigators to find “piles of cash,” “dozens of diamonds” and an expired passport with an alias and a Saudi Arabian address.

They also seized many photos of nude girls, Rossmiller said.

This article has been updated throughout.

If you or someone you know needs help, call 1-800-273-8255 for the National Suicide Prevention Lifeline. You can also text HOME to 741-741 for free, 24-hour support from the Crisis Text Line. Outside of the U.S., please visit the International Association for Suicide Prevention for a database of resources.