San Francisco District Attorney Chesa Boudin was at home cooking on Saturday afternoon when his dad, David Gilbert, called from a prison in upstate New York. Boudin was glad to hear his father’s voice. But he was worried about his old man: Someone in the cell next to him had tested positive for the coronavirus.

At 75, Gilbert is one of the oldest prisoners in the state. Even calling his son is risky for him now, since hundreds of guys at Shawangunk Correctional Facility share the same phones to call home. Before dialing his son, Gilbert wrapped the receiver with an undershirt to avoid touching it to his face. He would hand-wash the shirt after returning to his cell.

As the coronavirus sweeps through the country’s prisons and jails, Gilbert is one of the tens of thousands of elderly inmates at high risk for complications. In New York, about 2,600 prisoners were at least 60 years old in 2018. A greater number have other serious underlying conditions. Now Gilbert is part of a group of vulnerable inmates petitioning a court to protect them from the deadly virus by releasing them early.

In 1981, when Boudin was just 14 months old, his mother, Kathy Boudin, and Gilbert—both members of the leftist Weather Underground group—were arrested for serving as getaway drivers during the notorious Brinks heist, which resulted in the deaths of a company guard and two police officers. Boudin was raised in Chicago by his parents’ professor friends, fellow Weathermen Bill Ayers and Bernardine Dohrn. He got to know his own mother and father through phone calls. They liked to tell him fictional adventure stories—Gilbert calling to share a chapter one day, and Kathy Boudin following up later with another. She was paroled in 2003, the year Boudin became a Rhodes Scholar. Gilbert received a longer sentence and has many years left in prison. Boudin visited him last November, on the same day he learned he had been elected as San Francisco’s DA.