The New York City medical examiner's office said Sunday that it had completed an autopsy on the financier and accused sex trafficker Jeffrey Epstein but that it needed more information before determining the cause of death.

Multiple people briefed on the investigation told NBC News that suicide remains the presumed cause of death and that no sign of foul play has emerged in the day and a half since Epstein, 66, was found unresponsive in his federal jail cell in lower Manhattan on Saturday.

Epstein was not on suicide watch at the time of his death, even though he was found in his cell two weeks ago with marks on his neck, multiple people familiar with the investigation said.

Attorney General William Barr said Saturday that he was "appalled to learn that Jeffrey Epstein was found dead" while in federal custody. Barr said the Justice Department's inspector general was opening an investigation.

Unfounded conspiracy theories flourished online in the wake of Epstein's death, many of them trying to blame it on President Donald Trump or former President Bill Clinton, both of whom were associated with Epstein in the past.

The theories — at least one of which was shared by Trump himself — had no evidence to support the outlandish ideas, and authorities said at the time that they suspected no foul play.

The FBI does not normally look into suicides at a federal Bureau of Prisons facility, but a senior law enforcement official said that it was investigating given the nature of this case and out of an "abundance of caution."

Epstein's death came the day after a trove of court documents was unsealed, providing new details about his alleged sex trafficking.

He was arrested July 6 at an airport in Teterboro, New Jersey, as he returned from Paris on a private jet. He was charged with one count of sex trafficking conspiracy and one count of sex trafficking and could have faced up to 45 years in prison if convicted.

He pleaded not guilty and was denied bail.

The indictment said he sought out minors, some as young as 14, from at least 2002 through 2005 and paid them hundreds of dollars in cash for sex at either his Manhattan townhouse or his estate in Palm Beach, Florida, federal prosecutors revealed last month.

A federal appeals court unsealed almost 2,000 pages of documents Friday on Epstein and Ghislaine Maxwell, a British socialite and Epstein's former girlfriend. The documents relate to a 2015 defamation lawsuit filed against Maxwell by an alleged victim, Virginia Roberts Giuffre, which was settled out of court in 2017.

Giuffre, now 36, claimed in her 2016 deposition that among the high-profile men with whom Epstein and Maxwell ordered her to have sex were former New Mexico Gov. Bill Richardson, who was energy secretary and U.N. ambassador in the Clinton administration; former Senate Democratic leader George Mitchell of Maine; and Glenn Dubin, a prominent money manager. All have strongly denied the claims.

"There's a whole bunch of them — it's just hard for me to remember," Giuffre said, according to the court filing. "My whole life revolved around just pleasing these men and keeping Ghislaine and Jeffrey happy. Their whole lives revolved around sex."

Epstein's alleged victims said after his death Saturday they would have preferred to have their day in court and felt that Epstein had escaped justice.

Jennifer Araoz, who accused Epstein of raping her when she was 15 after she was recruited outside her New York City high school, said his death did little for the deep scars that she and her fellow victims still carry.

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

Former wardens and veterans of the federal prison system said that they were shocked by the decision to remove Epstein from suicide watch given his high-profile case.

"For them to pull him off suicide watch is shocking," Cameron Lindsay, a former warden who worked at three federal facilities, said. "For someone this high-profile, with these allegations and this many victims, who has had a suicide attempt in the last few weeks, you can take absolutely no chances."

Multiple people briefed on the investigation said that Epstein underwent a psychiatric evaluation on or about July 29, after which he was cleared from suicide watch and returned to a cell in the Special Housing Unit.