A Louisiana prison guard sat alongside a sick inmate for more than an hour inside a van and his hospital room, told by a supervisor he didn’t need a mask despite the prisoner’s severe cough and other telltale signs of Covid-19.

Within 10 days, the 49-year-old inmate, Patrick Jones, was dead from the coronavirus. The officer, Aubrey Melder, was back at work, having been told days earlier to return, without quarantining, to his duties inside the low-security prison in Oakdale, a lawyer for the union representing prisons employees said.

The prison, 200 miles west of New Orleans, has emerged as a focal point of the coronavirus pandemic inside the nation’s lockups. Five prisoners have died there from the disease, the most of any federal prison. At least 25 inmates and 21 workers have tested positive, including seven prisoners who are in intensive care and four on ventilators; two employees are also hospitalized, according to data from officials at the facility. The actual figure is almost certainly higher as there is little testing.

Interviews with inmates and their families, corrections officers and local officials show a prison under siege by an invisible enemy. Inside cells holding six men each, feverish, coughing inmates at times weren’t separated from their healthy cellmates, but instead lay in their bunks an arm’s length away. Some fashioned masks from their own clothing. Inmates say they can hear coughing throughout the halls every night.

“Our sentences have turned into death sentences,” Sterling Rivers, a 32-year-old from Tennessee serving time at Oakdale for a drug conspiracy conviction said in an interview.