An autopsy has concluded that financier Jeffrey Epstein died by suicide, the New York City medical examiner's office says.

Key points: Conspiracy theories have persisted since Mr Epstein's death on August 10

Conspiracy theories have persisted since Mr Epstein's death on August 10 The FBI and the US Justice Department are both investigating the death

The FBI and the US Justice Department are both investigating the death Mr Epstein had been taken off suicide watch after being found on his cell floor last month

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Mr Epstein, 66, was found dead in his cell at the Metropolitan Correctional Centre in New York City on August 10, sparking outrage and disbelief over how such a high-profile prisoner, known for socialising with powerful people including US presidents Donald Trump and Bill Clinton, could have gone unwatched.

The FBI and the Justice Department's inspector-general are both investigating Mr Epstein's death.

Attorney-General William Barr says officials have uncovered "serious irregularities" at the jail.

Mr Barr this week ordered the removal of the warden at the jail, the Justice Department said.

Mr Epstein, a convicted sex offender who was facing additional charges of sexually abusing numerous underage girls over several years, had been placed on suicide watch last month after he was found on his cell floor on July 23.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 33 seconds 33 s Van reportedly carrying Jeffrey Epstein's body leaves hospital

But multiple people familiar with operations at the jail say he was taken off the watch after about a week and put back in a high-security housing unit where he was less closely monitored, but still supposed to be checked on every 30 minutes.

Jail guards on duty the night of Mr Epstein's death are suspected of falsifying log entries to show they were checking on inmates every half-hour as required, according to several people familiar with the matter.

A guard in Epstein's unit was working a fifth straight day of overtime and another guard was working mandatory overtime, the people said.

They spoke on condition of anonymity because they lacked authorisation to publicly discuss the investigation.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 36 seconds 36 s William Barr says "serious irregularities" were found at Epstein's prison

Women sue Epstein's estate, alleging sexual abuse

The medical examiner's ruling came a day after two more women sued Epstein's estate, saying he sexually abused them.

The suit, filed on Thursday in a federal court in New York, claims the women were working as hostesses at a popular Manhattan restaurant in 2004 when they were recruited to give Epstein massages.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 1 minute 34 seconds 1 m 34 s Jennifer Araoz says she was raped by Jeffrey Epstein when she was 15

One was 18 at the time. The other was 20.

The lawsuit says an unidentified female recruiter offered the hostesses hundreds of dollars to provide massages to Epstein, saying he "liked young, pretty girls to massage him," and wouldn't engage in any unwanted touching. The women say Epstein groped them anyway.

One plaintiff now lives in Japan, the other in Baltimore.

They seek US$100 million ($147 million) in damages, citing depression, anxiety, anger and flashbacks.

Other lawsuits, filed over many years by other women, accused him of hiring girls as young as 14 or 15 to give him massages, then subjecting them to sex acts.

ABC/wires