Jeffrey Epstein was a wealthy US financier who was surrounded by powerful and famous people. He was also a convicted sex offender who was facing new sex trafficking charges that could have put him in prison for the rest of his life.

On Saturday, he apparently took his own life in his jail cell.

Americans from both sides of politics are asking how it was allowed to happen just weeks after a previous suspected suicide attempt.

The mysterious Mr Epstein's life and crimes, and the lack of punishment thereof, had already been the subject of intense debate, but his death has prompted a slew of new conspiracy theories.

Meanwhile, his accusers were dismayed that he would never face justice or reveal "dark secrets".

Who was Jeffrey Epstein?

Jeffrey Epstein was arrested on sexual abuse charges. ( Reuters: Florida Department of Law Enforcement )

Though he never finished college, Mr Epstein started his career as a maths teacher at New York's elite Dalton School. He soon went on to work at the investment bank Bear Stearns in the early 1980s.

In 1982 he started his firm J Epstein and Co, successfully pitching himself to billionaire clients.

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Though his personal wealth was never revealed publicly, outwardly he appeared tremendously wealthy, leading an extravagant lifestyle.

His enterprise was, for tax purposes, run from the small Caribbean island of Little St James, which he owned. By 1992 he owned the largest private residence in Manhattan. In 2003, he donated $9.6 million to a mathematical biology program at Harvard University.

He also owned an estate at Palm Beach, Florida, a ranch in New Mexico, an apartment in Paris, multiple luxury cars, valuable artworks, a Gulfstream G550 jet, a helicopter and a Boeing 727-200 nicknamed the "Lolita Express", according to Business Insider.

But it was not Mr Epstein's money that made his case so intriguing to the public, it was the company he kept.

Mr Epstein owned Little St James Island in the US Virgin Islands. ( Reuters: Marco Bello )

He was friends with Britain's Prince Andrew, actors Kevin Spacey and Woody Allen, Harvard Law professor emeritus Alan Dershowitz, Leslie Wexner, the billionaire behind Victoria's Secret, and British socialite Ghislaine Maxwell, daughter of the late press baron Robert Maxwell.

Most famously, he associated with US President Donald Trump in the late '90s and early 2000s — regularly visiting Mr Trump's Mar-a-Lago Club — and former president Bill Clinton, who flew on the "Lolita Express" 26 times, according to the jet's logs.

Mr Clinton says his interactions with Mr Epstein were purely aligned with charity work, while Mr Trump, who once called him "a lot of fun to be with", said in July the pair had fallen out long ago and he didn't consider him a friend.

In a 2002 New York Times profile, Mr Epstein was described as a mysterious, Wizard of Oz-type figure and "Gatsbyesque".

The first trial

Alex Acosta worked on Mr Epstein's case before he became the US Secretary of Labor. ( Reuters: Carlos Barria )

It was Mr Epstein's light punishment in 2008, after pleading guilty to state charges of soliciting a minor party for prostitution, that stoked scepticism from many observers that justice was being administered fairly.

The deal, brokered by Mr Trump's future labour secretary Alexander Acosta, saw the convicted paedophile avoid a possible life sentence and spend just 13 months in jail — of which he was allowed day release for work.

Mr Acosta resigned last month after coming under fire for overseeing that deal.

It was the work of Miami Herald investigative journalist Julie K Brown, looking into the details of Mr Acosta's plea deal with Mr Epstein, that sparked renewed interest in the affair, and eventually led to the new charges for alleged crimes between 2002 and 2005, this time on a federal rather than a state level.

Before his legal troubles, Mr Epstein led a life of extraordinary luxury. ( AP: Elizabeth Williams )

A day before he took his own life, new documents about his alleged global sex-trafficking ring and the way it was operated were unsealed by the court.

He faced up to 45 years behind bars.

How were his 'dark secrets' allowed to die with him?

The Metropolitan Correctional Center where Jeffrey Epstein was being held. ( Reuters: Jeenah Moon )

Mr Epstein had been placed on suicide watch and given daily psychiatric evaluations after an incident a little over two weeks ago in which he was found unconscious in his cell, according to a person familiar with the matter who wasn't authorised to discuss it publicly.

It hasn't been confirmed whether the injuries he sustained were self-inflicted or the result of an assault.

Mr Epstein was taken off suicide watch at the end of July, the person told AP.

The FBI and the Department of Justice's Inspector General were opening investigations, US Attorney-General William Barr said, adding that he was "appalled" to learn of his death in federal custody.

"Mr Epstein's death raises serious questions that must be answered," Mr Barr said in a statement.

The Bureau of Prisons confirmed that he had been housed in the jail's Special Housing Unit, a heavily secured part of the facility that separates high-profile inmates from the general population.

Until recently, the same unit had been home to the Mexican drug lord Joaquin "El Chapo" Guzman, who is now serving a life sentence at the so-called Supermax prison in Colorado.

Mr Acosta resigned from his position of labour secretary when Mr Epstein was brought to trial in July. ( AP: Andrew Harnik )

Mr Epstein's death raises questions about how the Bureau of Prisons ensures the welfare of such high-profile inmates. In October, Boston gangster James "Whitey" Bulger was killed in a federal prison in West Virginia where he had just been transferred.

Nebraska senator Ben Sasse, a Republican member of the Senate Judiciary Committee, wrote in a scathing letter to Mr Barr that "heads must roll" after the incident.

"Every single person in the Justice Department — from your main Justice headquarters staff all the way to the night-shift jailer — knew that this man was a suicide risk, and that his dark secrets couldn't be allowed to die with him," Mr Sasse wrote.

Cameron Lindsay, a former warden who ran three federal lockups, said the death represents "an unfortunate and shocking failure, if proven to be a suicide".

"Unequivocally, he should have been on active suicide watch and therefore under direct and constant supervision," Mr Lindsay said.

Preet Bharara, a former federal prosecutor in Manhattan, wrote on Twitter that Mr Epstein's suicide was likely recorded on prison cameras.

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'I am angry': Politicians, victims demand answers

Florida Republican senator Rick Scott said in a statement that systematic failures had hurt the alleged victims.

"The victims of Jeffrey Epstein's heinous actions deserved an opportunity for justice. Today, that opportunity was denied to them," he said

"The Federal Bureau of Prisons must provide answers on what systemic failures of the MCC Manhattan or criminal acts allowed this coward to deny justice to his victims."

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Jennifer Araoz, who accused Mr Epstein of raping her when she was 15, said it was up to authorities now to pursue justice.

"I am angry Jeffrey Epstein won't have to face his survivors of his abuse in court," she said in a statement to NBC News.

"We have to live with the scars of his actions for the rest of our lives, while he will never face the consequences of the crimes he committed, the pain and trauma he caused so many people.

"Epstein is gone, but justice must still be served. I hope the authorities will pursue and prosecute his accomplices and enablers, and ensure redress for his victims."

Conspiracy theories abound

Speculation that powerful figures were involved in the apparent suicide was rife on social media platforms, with #ClintonBodyCount and #TrumpBodyCount trending on Twitter.

The world's most prominent user of the platform, Mr Trump retweeted one such conspiracy theorist who linked Mr Clinton to the death.

"Jeffery Epstein had information on Bill Clinton and now he's dead," actor-comedian Terrence K Williams wrote.

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Mr Trump's lawyer and former mayor of New York, Rudy Giuliani, also bought into the premise that someone else was involved.

"Who was watching? What does the camera show? … Follow the motives," he wrote.

Elsewhere online there was unsubstantiated speculation that Mr Epstein's death wasn't a suicide, or indeed that his death was faked.

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In a court filing on July 25, the Government said it was pursuing an "ongoing investigation of uncharged individuals" in connection with the case against Mr Epstein.

That investigation, in the US Attorney's office in Manhattan, will continue despite Mr Epstein's death, a different source familiar with the matter said.