Corrections officers had not checked in on financier and registered sex offender Jeffrey Epstein for “several” hours before he was found hanging in his cell Saturday, a person familiar with the matter said, just one in a series of missteps in the hours leading up to his death.

Officers should have been checking on Epstein, who was being held in a special housing unit of the Metropolitan Correctional Center in New York City, every 30 minutes, and, under normal circumstances, he also should have had a cellmate, according to the person familiar with the matter and union officials representing facility employees.

But a person who had been assigned to share a cell with Epstein was transferred on Friday, and — for reasons that investigators are still exploring — he did not receive a new cellmate, the person familiar with the matter said Sunday night. That left Epstein, who had previously been placed on suicide watch, alone and unmonitored — at least in the hours before his death — by even those officers assigned to guard him.