Jeffrey Edward Epstein was an American financier and convicted sex offender. Epstein began his career in finance at the investment bank Bear Stearns, before forming his own firm, J. Epstein & Co.

Epstein has been discovered dead in jail where he had been held pending trial on federal sex trafficking charges.

The 66-year-old billionaire investor had been accused of sex trafficking girls as young as 14 for himself and a number of his high-profile mates — including elite politicians, royalty and celebrities. He was being held without bail in a Lower Manhattan jail cell after being arrested on 6 July.

He pleaded not guilty and faced up to 45 years in prison.

Epstein hanged himself. He was found unresponsive in his cell at Metropolitan Correctional Center in Lower Manhattan around 6:30 a.m., the Bureau of Prisons said. He was transported in cardiac arrest at 6:39 a.m. to New York Downtown Hospital, where he was pronounced dead, according to sources.

Epstein had previously been moved to a suicide-watch unit after being found unconscious in his cell with marks on his neck on July 23, a week after his bail request had been rejected. The news of his death has been met with disbelief on social media. Reports are emerging that Epstein was taken off suicide watch on the 29th of July.

He socialised with princes and presidents and lived on a 100-acre private island in the Caribbean and one of the biggest mansions in New York.

A college dropout, he became a sought-after benefactor of professors and scientists, donating millions of dollars in donations to Harvard University and other causes. Still, it was never entirely clear how the middle-class Brooklyn maths whiz became a Wall Street master of high finance.

The somewhat reclusive Epstein splashed into the news in 2002 after a New York tabloid reported he had lent his Boeing 727 to ferry former President Bill Clinton and other notables on an AIDS relief mission to Africa.

His friends over the years have included Donald Trump, Britain’s Prince Andrew and former Harvard law professor Alan Dershowitz.

But Epstein also enjoyed surrounding himself with women much younger than he, including Russian models who attended his cocktail parties and beautiful women he flew aboard his plane.

The deposition happened almost three years before Epstein’s July 6 arrest on sex trafficking charges in a case that has brought down a Cabinet secretary and launched fresh investigations into how authorities dealt with Epstein over the years.

The 66-year-old pleaded not guilty.

Epstein was asked in the videotaped deposition whether it was the standard operating procedure for his former girlfriend, Ghislaine Maxwell, to bring underage girls to him to sexually abuse.

Epstein replied “Fifth,” as he did to numerous other questions, citing the Constitution’s Fifth Amendment that protects people against incriminating themselves.

Epstein’s lawyers say the federal charges that accuse Epstein of recruiting and abusing dozens of underage girls in New York and Florida in the early 2000s should never have been brought.

They say Epstein is protected by an agreement he reached with federal prosecutors in Florida a dozen years ago. Labor Secretary Alexander Acosta resigned last month after coming under fire for overseeing that deal when he was US lawyer in Miami.

At the time of Epstein’s arrest, prosecutors said they found a trove of pictures of nude and semi-nude young women and girls at his $US77 million Manhattan mansion.

They also say additional victims have come forward since the arrest.