Experts warn the population at large is at risk if prisons are not protected from disease.
Earlier this year, California officials brought busloads of imprisoned men from a coronavirus hotspot to the overcrowded San Quentin prison.
They had not tested some of the transferred men for COVID-19 for a month.
The bungled transfer sparked one of the country’s worst outbreaks. More than half the men imprisoned at San Quentin have been infected, and 28 have died.
The pandemic put a spotlight on prison overcrowding, and in October, a court ordered San Quentin to drastically reduce its population.
We investigate how a prison system endangered jailed people and staff, and meet loved ones on the outside grappling with loss.