Epstein was found unresponsive in his cell in the Metropolitan Correctional Center's special housing unit at approximately 6:30 a.m. ET "from an apparent suicide," according to Lee Plourde, a spokesperson for the Federal Bureau of Prisons.
"Life-saving measures were initiated immediately by responding staff," he said in a statement.
Epstein was taken to a local hospital, where staff continued to try to revive him. Pictures published by the New York Post showed a lifeless Epstein being wheeled into a downtown hospital by paramedics.
A spokesperson for the Manhattan medical examiner's office confirmed to BuzzFeed News that Epstein had died. "We have opened an investigation," the spokesperson added.
Late last month, the New York financier — whose former associates included President Donald Trump, Prince Andrew, and former president Bill Clinton — was found injured in his cell from a suspected suicide attempt.
The FBI is now investigating the circumstances around his death.
Attorney General Bill Barr said he was "appalled" to learn of Epstein's apparent suicide. He said the Department of Justice inspector general would also open its own investigation in addition to the FBI probe. "Mr. Epstein’s death raises serious questions that must be answered," said Barr.
"We need answers," tweeted Rep. Alexandria Ocasio-Cortez, who represents part of New York City. "Lots of them."
Epstein, 66, was arrested last month and accused of running a sex trafficking operation in which he allegedly sexually abused dozens of underage girls, some as young as 14, in his New York and Florida homes between 2002 and 2005. He had pleaded not guilty.
The billionaire was accused of paying dozens of underage girls to give him nude "massages" in which he then sexually abused them. He then allegedly paid some of his victims to recruit other girls to be abused.
Epstein was arrested July 6 and denied bail after Judge Richard Berman deemed him a flight risk. He was facing a maximum of 45 years in prison after being charged with one count of sex trafficking of minors and one count of conspiracy to engage in sex trafficking of minors.
Geoffrey Berman, the US attorney for the Southern District of New York, had told reporters after the arrest that bringing charges against Epstein was “profoundly important to the many alleged victims who are now young women.”
“They deserve their day in court,” he said.
During a bail hearing for Epstein in July, Assistant US Attorney Alex Rossmiller said authorities found a safe in Epstein's home with pictures of naked women, cash, diamonds, and a fake foreign passport with the financier's photo in it. The charges, Rossmiller also said, made Epstein a risk to society, and he was subsequently denied bail.
In 2008, Epstein pleaded guilty to a charge of soliciting prostitution and served 13 months in jail. He was also required to register as a sex offender. But he had initially been accused of sexually abusing and trafficking dozens of underage girls at his home in Palm Beach, Florida — charges for which he could have faced life in prison.
Alex Acosta, who was then the US attorney for the Southern District of Florida, had offered Epstein a lenient plea deal that also granted immunity to “any potential co-conspirators." The deal was also concealed from Epstein's victims until a judge approved it.
After Epstein's arrest last month, Acosta resigned from his role as Trump's labor secretary amid renewed criticism of how he prosecuted the case nearly a decade ago. In an announcement to reporters at the time, the president said it was Acosta's own decision to leave the administration.