Washington (CNN) The Justice Department's inspector general is opening an investigation into the circumstances surrounding the death of multimillionaire financier and accused sex trafficker Jeffrey Epstein, Attorney General William Barr announced on Saturday.

The Federal Bureau of Prisons confirmed Epstein's death, saying he was found unresponsive in his cell on Saturday at New York's Metropolitan Correctional Center around 6:30 a.m. ET. The bureau's release called it "an apparent suicide," and said the FBI is investigating. Two law enforcement sources told CNN that Epstein died by suicide.

Barr said he was "appalled" to learn of Epstein's death while in federal custody awaiting trial.

"I was appalled to learn that Jeffrey Epstein was found dead early this morning from an apparent suicide while in federal custody. Mr. Epstein's death raises serious questions that must be answered," Barr said in a statement. "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."

Epstein had been jailed since early July, when he pleaded not guilty to charges by New York federal prosecutors after an indictment accused him of sex trafficking dozens of underage girls, some as young as 14 years old.

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