The US Justice Department has already found “serious irregularities” at the federal jail where Jeffrey Epstein took his own life over the weekend, US attorney general William Barr has said.
Mr Barr said he was angry to learn that staffers at the Metropolitan Correctional Centre in New York had “failed to adequately secure this prisoner”.
Epstein died on Saturday in what prison officials said was an apparent suicide.
He was awaiting trial on sex trafficking charges.
Mr Barr did not provide specific details but said investigations by the FBI and the Justice Department inspectors general are continuing.
He was speaking at a police conference in New Orleans.
Mr Barr also issued a stern warning, saying the case was far from over.
He said anyone who may have conspired with Epstein “should not rest easy”.