Prisoners played joyous arrangements in harrowing circumstances.

“Sing a Song When You’re Sad.” “The Most Beautiful Time of Life.” For songs arranged by inmates and performed at a death camp, the upbeat titles are jarring.

Dr. Patricia Hall, a University of Michigan professor of music theory, says she was “completely thrown” by what she found in the card catalogs at the Auschwitz-Birkenau Museum in Poland when she visited to learn more about music performed by prisoners at the camp. Since 2016, Hall has found several musical arrangements handwritten by Auschwitz inmates to match the instruments and musicians available.

But just finding the music wasn’t enough. Hall enlisted university conductor Oriol Sans and graduate student Josh Devries to transcribe the handwritten sheet music into notation software that makes it easier for musicians to read. University musicians recorded “The Most Beautiful Time of Life”—a popular fox trot during the war—and performed it at a free concert on campus last November.

“You want people to be able to hear what these pieces sound like,” Hall told the Associated Press. “It’s one thing to study something in an archive, but it’s quite another to, as I say, give it a voice, give it life.”

Hall believes the piece was performed by prisoners at one of the camp commandant’s Sunday concerts in 1942 or 1943.

Hall was able to identify two of three inmate arrangers from prison identification numbers handwritten on one of the scores: Polish political prisoners Antoni Gargul and Maksymilian Pilat, both of whom survived the camp. Pilat later played with Poland’s Gdansk symphony.

The Auschwitz musicians were better fed, clothed, and treated than other inmates, but Hall said at least 50 still were executed. Overall, 1.1 million people, mostly Jews, are believed to have died at Auschwitz-Birkenau.

Hall says there are more Auschwitz arrangements worth recording and performing. But she’s not sure she’s up to it. “I find the atmosphere at Auschwitz-Birkenau quite depressing,” she said. “I go back and forth about how much further I’m going to research these manuscripts.”

Still, she notes, “One of the messages I’ve taken from this is the fact that even in a horrendous situation like a concentration camp, that these men were able to produce this beautiful music.”