Two jail guards who were on duty when Jeffrey Epstein killed himself browsed the internet and napped during the night before his body was found, instead of checking on him every half-hour as they were required to do, prosecutors have said. The guards then lied, prosecutors said, on official logs, indicating that they had made the rounds when they had not.

Attorney General William P. Barr said last week that Mr. Epstein’s death resulted from “a perfect storm of screw-ups.”

But lawyers for the guards, who have been criminally charged, suggested in court on Monday that their clients were being made into scapegoats for larger problems in the federal prison system that contributed to Mr. Epstein’s death.

The Manhattan jail where Mr. Epstein hanged himself has long been plagued by staff shortages and the two guards, Michael Thomas and Tova Noel, had already done several tours of overtime that week.