Disgraced financier Jeffrey Epstein was found dead early on Saturday after an apparent suicide in his lower Manhattan jail cell where he was being held without bail on federal sex-trafficking charges.
According to media reports last month he was found unconscious on the floor of his jail cell with marks on his neck.
Officials were investigating that incident as a possible suicide or assault.
A source familiar with the matter said that at the time of his death, he was not on suicide watch.
U.S. Attorney General William Barr said in a statement on Saturday he was "appalled" by the news and that his "raises serious questions that must be answered," adding that the FBI will investigate.
Epstein was arrested on July 6 and pleaded not guilty to federal charges of sex trafficking involving dozens of underage girls as young as 14, from at least 2002 to 2005.
The charges against Epstein were announced more than a decade after he pleaded guilty in Florida to state prostitution charges after a deal with prosecutors that has been widely criticized as too lenient.
With his multimillion dollar apartments, private islands and jets, the well-connected money manager was known for socializing with politicians and royalty.
Over the years, he counted now President Donald Trump and former Democratic President Bill Clinton as his friends, and, according to court papers, Britain's Prince Andrew.
His death comes just hours after the unsealing of a court filing on Friday in a civil lawsuit, in which a woman who accused Epstein of keeping her as a sex slave said one of the financier's associates had instructed her to have sex with at least a half-dozen prominent men.
Despite Epstein's death, a source tells Reuters the investigation is far from over.
In another court filing on July 25, the government said it was pursuing an "ongoing investigation of uncharged individuals" in connection with the sex-trafficking case against Epstein.