The two prison guards assigned to watch Jeffrey Epstein on the night he died by suicide fell asleep during their shift and failed to check on the accused sex trafficker for about three hours, The New York Times reported Tuesday, citing a law enforcement official and a prison official familiar with the investigation into the 66-year-old financier’s death.

NBC News said investigators were probing whether the two guards had been asleep when Epstein died in his cell at Manhattan’s Metropolitan Correctional Center on Saturday. Law enforcement sources told the network that no conclusions had yet been made about whether the guards had been sleeping.

According to earlier reports, the pair, who have not been identified by the Justice Department, may have falsified log entries to show they were checking on inmates in the unit where Epstein was held every half hour — even though they hadn’t actually carried out this task. If true, such falsification could constitute a federal crime, the Times noted.

The two guards ― one of whom was not a full-fledged correctional officer ― have been placed on administrative leave in the wake of Epstein’s death. The warden of the jail, Lamine N’Diaye, has been temporarily reassigned.