Walter Turner, 42, had been held on Rikers Island on gun and drug charges for about a week when he began complaining of severe stomach pain in late April. Given only Tylenol by jail medical staff, he visited the jail clinic about six days later, and a doctor noted that his heart rate was elevated and his stomach was swollen and tender, according to jail records and Mr. Turner’s mother, Roslyn Greene-Turner. He was taken to Elmhurst Hospital that evening, where testing showed he was septic and in need of immediate surgery.

On the operating table, Mr. Turner went into cardiac arrest and suffered a decrease in brain function, according to his lawyer, Patrick Watts, Ms. Greene-Turner and records obtained by The Times. After multiple surgeries, doctors concluded he would never regain “meaningful consciousness,” jail records show.

As Ms. Greene-Turner was still absorbing that news, Mr. Molina arrived at the hospital and promised to see the charges against Mr. Turner dropped and to “get him out of custody,” she said. But Ms. Greene-Turner initially refused, concerned it would mean the jail system would escape scrutiny for what she considered lapses in her son’s care — and that she would be saddled with the resulting medical bills.

Soon after, another city official reached out about granting Mr. Turner a compassionate release, she said, but again she declined. Only after she realized that Mr. Turner could not be transferred to a long-term care center while he was still incarcerated, and her family’s access to him was restricted to allow not even a pastor to visit, did she relent, she said. She added that she believed the restrictions were meant to pressure her into giving her consent.

In June, Mr. Turner was transferred to a nursing facility in the Bronx.

“I wanted them to be accountable,” said Ms. Greene-Turner, 75. “They put him in the hospital.”