One of the two people guarding Jeffrey Epstein when he apparently hanged himself in a federal jail cell was not a full-fledged correctional officer, and neither guard had checked on Mr. Epstein for several hours before he was discovered, prison and law-enforcement officials said. Those details emerged on Monday as Attorney General William P. Barr sharply criticized the management of the federal jail in Manhattan where Mr. Epstein, who was accused of sexually abusing dozens of teenage girls, was found dead on Saturday morning. “We are now learning of serious irregularities at this facility that are deeply concerning and demand...