Wealthy financier Jeffrey Epstein was found semi-conscious in his prison cell on Thursday, US media reports say.
The 66-year-old, who is awaiting trial on sex trafficking charges, was reportedly found sprawled on the floor with injuries to his neck on Wednesday.
The cause is unclear – neither suicide attempt nor assault has been ruled out. He has been at the New York facility since being denied bail last week.
Epstein has pleaded not guilty to sex trafficking and conspiracy charges.
The US Bureau of Prisons issued a statement saying that Epstein was, as of noon local time (16:00 GMT), at New York’s Metropolitan Correctional Center and “not in a local hospital as has been reported”.
But it was not clear if he had been treated for injuries either at a hospital or the prison, with officials saying “we do not share information on an inmate’s medical status or their conditions of confinement”.
He was taken to a nearby hospital in Manhattan, reports say, but his condition has not been made public. Investigators are working to establish what happened.
What is he charged with?
According to the indictment, the financier is accused of paying girls under the age of 18 to perform sex acts at his Manhattan and Florida mansions between 2002 and 2005.
Epstein, who was arrested on 6 July after landing in New Jersey on his private jet, avoided similar charges in a controversial secret plea deal in 2008, and instead pleaded guilty to a lesser charge.
That plea deal has come under increasing scrutiny and, earlier this month, US Labor Secretary Alex Acosta resigned over his role in it.
Prosecutors also accuse Epstein of paying large amounts of money to two potential witnesses during the forthcoming trial.
He has pleaded not guilty to all the charges. If convicted, he faces up to 45 years in prison.
He was denied bail last Thursday but his lawyers have appealed against the decision.
Who is Jeffrey Epstein?
New York-born Epstein worked as a teacher before moving into finance.
Prior to the criminal cases against him, he was best known for his wealth and high-profile connections.
He has long been surrounded by the rich and powerful, including President Donald Trump, former President Bill Clinton and the UK’s Prince Andrew.
In a 2002 profile in New York Magazine, Mr Trump referred to Epstein as a “terrific guy”.
“He’s a lot of fun to be with,” he said. “It is even said that he likes beautiful women as much as I do, and many of them are on the younger side.”
However, Mr Trump has said the pair fell out “12 or 15 years ago” and reiterated on Friday that he was “not a fan of Jeffrey Epstein”.
Reports of Epstein’s current wealth vary, with his Virgin Islands-based firm generating no public records.