When we think of the harm that befalls soldiers during wartime, specific images come to mind. The fallout from scientific experiments — especially those carried out by our own government — isn’t one. But that was the reality of tens of thousands of military men in the 1940s, who were poisoned with mustard gas by the U.S. government to see how their bodies would react. It took decades to bring to light the vast scope of the experiments, and it couldn’t have been completed without the work of two NPR journalists.

For years, veterans were sworn to secrecy about the tests, prohibited from even discussing them with doctors. While this curtain was lifted in the 1990s, and Congress and the U.S. Department of Veterans Affairs promised medical care and services, many vets didn’t get it. NPR reporter Caitlin Dickerson and research librarian Barbara Van Woerkom found records for and called hundreds of vets who were used in these experiments, and their work paved the way for the men — who are now well into their 80s — to receive the care and recognition they needed.

Dickerson was new to the investigative desk when she began working with Van Woerkom, who’d been gnawing around the edges of the story for years. She said she understood right away the urgency of what Van Woerkom was sitting on. “There was also this element of time, because most of the men who were used in these tests had died, and those who were still around were in their 80s or 90s,” she said. “It felt sort of dire.”