Last year I published a book, “Blood in the Water,” that offered the first comprehensive account of the uprising at New York’s Attica Correctional Facility in 1971 and its legacy. Though this protest against systematic abuse and abysmal living conditions — in which nearly 1,300 prisoners took over the facility, and law enforcement ultimately shot 128 men, killing 39 — was a cultural and political touchstone of the 1970s, much of the story was covered up. Attica is a public institution, but its records are not easily accessible. With no statute of limitations on murder, state officials had much to protect.

So I had to dig, for 13 years, to uncover what had really happened. But even more than a decade of research didn’t turn up everything.

Recently I received a message from a freelance writer, Eric Beaumont, who had a question about a paragraph in my book that mentioned a doctor conducting experiments at Attica on prisoners. It read:

The doctor knew that he needed volunteers for his ongoing research, but finding a stable population of volunteers was “not easy,” therefore he was most grateful when he got permission to use Attica’s men. Because becoming a test subject offered the men in Attica some needed money, more than a few agreed to be exposed to the test virus. Although the doctor made sure the prisoners signed an informed consent agreement, as he later conceded, one “could argue about how informed they were.”

Who was this doctor, Mr. Beaumont asked, and did I know anything more about the experiments that he had been conducting?

I could at least answer the first question easily. The physician’s name was Michael W. Brandriss. However, despite having filed numerous Freedom of Information Act requests with the National Institutes of Health, as well as with the hospitals and the New York Department of Corrections that allowed him to work on their premises, I could never establish what exactly Dr. Brandriss was testing.

The next day, Mr. Beaumont messaged me again. He had found an article from a 1972 medical journal, written by Dr. Brandriss and two other physicians. Its title: “An Evaluation of Transfer Factor as Immunotherapy for Patients with Lepromatous Leprosy.”...