Jeffrey Epstein, the Manhattan- and South Florida-based financier who was held for charges of sex trafficking, was found dead in a secure housing unit of the federal Metropolitan Correctional Center in New York early Saturday morning.

Prison officials said Epstein was found unresponsive in his cell around 6:30 a.m. and was treated by jail staff and emergency responders. He was taken to a local hospital, where he was later pronounced dead.

The U.S. Department of Justice said the FBI was investigating the incident.

Epstein, 66, was awaiting trial in the Southern District of New York on charges that he ran an underage sex ring out of his homes in Manhattan and Palm Beach. Prosecutors in the Southern District of New York alleged that Epstein had paid girls as young as 14 for sex and to recruit new victims into his network.

The U.S. Attorney’s Office in Manhattan declined to immediately comment Saturday morning. Epstein’s lawyers, Boston-based Martin Weinberg of Martin G. Weinberg P.C. and Reid Weingarten of Steptoe & Johnson, did not respond to calls seeking comment on their client’s death.

U.S. Attorney General William Barr said in a statement that an FBI investigation had been opened into Epstein’s death.