Surveillance video from disgraced financier Jeffrey Epstein's first suspected suicide attempt was destroyed by accident, prosecutors say.
US prosecutors say the jail mistakenly saved footage from the wrong cell.
Epstein, a convicted sex offender, first tried to kill himself in July last year, then hanged himself in jail in August while awaiting trial on federal sex-trafficking charges.
He had pleaded not guilty to abusing dozens of girls, some as young as 14.
Soon after Epstein's death, in August, two of the CCTV cameras outside his cell had malfunctioned and were being examined by the FBI, US media reported.
Epstein was found semi-conscious in his prison cell with injuries to his neck on 25 July. After this incident, he was placed on suicide watch.
Eventually, Epstein was moved to a different cell, where he died on 10 August. Two prison guards have since been accused of failing to check on him during this time and falsifying records to say that they had.
There have been ongoing questions over the July recording, which was initially deemed missing and then was said to have been located by jail staff.
A letter filed by Assistant US Attorneys Jason Swergold and Maurene Comey said "the footage contained on the preserved video was for the correct date and time, but captured a different tier than the one where Cell-1 was located", New York City media report.
"The requested video no longer exists on the backup system and has not since at least August 2019 as a result of technical errors."
The request for the video was made by a lawyer for Nicholas Tartaglione, a former New York police officer who shared a cell with Epstein in July and is charged with homicide in an unrelated case.
The attorney argued the video could show his client had acted "admirably", possibly helping Epstein.
The Federal Bureau of Prisons did not immediately respond to a request for comment from the BBC.
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 was often seen socialising with the rich and powerful, including US President Donald Trump, former President Bill Clinton and the UK's Prince Andrew.
Epstein was accused of paying girls under the age of 18 to perform sex acts at his Manhattan and Florida mansions between 2002-05. He was arrested on 6 July.
He avoided similar charges in a controversial deal in 2008, pleading guilty to a lesser charge of soliciting and procuring a minor for prostitution.