Epstein, 66, was found hanging in his cell on Saturday morning, and soon afterwards the Office of Chief Medical Examiner of the City of New York confirmed him dead, though the autopsy was still pending, reports Efe news.
Epstein's death occurred several weeks after he was found unconscious in his cell on July 23 with marks on his neck. Authorities were investigating whether he had tried to commit suicide.
After that incident he was moved to a facility designed to prevent suicide attempts and whose efficiency local media are now questioning.
His demise immediately aroused multiple reactions including that of US Attorney General William Barr, who said he was "appalled" that this could have occurred in federal government custody.
"Epstein's death raises serious questions that must be answered," Barr said in a statement.
He added that besides the ongoing Federal Bureau of Investigation underway, the Justice Department will carry out its own scrutiny.
Epstein, who founded his company in 1982, was arrested on July 6 when his private plane landed in New Jersey and he was whisked off to New York to face charges before the US District Court of the Southern District of New York.
He was accused of creating a network for trafficking underage girls for sex at his mansions in New York and Florida for the past 10 years. He declared himself not guilty.
According to the accusation, Epstein was aided by employees and associates to entice girls into his residences, paying them hundreds of dollars to have sex with him and also to recruit other victims.
The magnate tried to pay his way out of prison while awaiting trial, scheduled for next year, with an offer of up to $100 million in bail. The judge refused the offer, however, with the argument that Epstein was a danger to society and could easily escape.
His lawyers regretted his death and said in a statement that "no one should die in jail".
His death occurred a day after a New York federal appeals court judge ordered the unsealing of hundreds of pages of court documents containing new details of sexual abuse allegations against Epstein.
( With inputs from IANS )