OSWIECIM, Poland — The letter to Daniel Libeskind’s father arrived shortly after the war ended. His sister, Rozia, informed him that his family was dead. She was the only one of 10 siblings to survive Auschwitz. Over three handwritten pages in Yiddish, she detailed the horrors they endured.

“As I write these words,” she concluded, “who will believe what I am telling you?”

As the 75th anniversary of the liberation of the world’s largest factory of death approaches, Mr. Libeskind, the architect and artist, returned to the site of his family’s destruction, doing his part to be sure that her words — and the words of other witnesses — are both believed and not forgotten.

Working with the photographer Caryl Englander and the curator Henri Lustiger Thaler of the Amud Aish Memorial Museum in Brooklyn, Mr. Libeskind was at the Auschwitz-Birkenau State Museum on Monday to open a new temporary exhibit — “Through the Lens of Faith” — near the entrance to the camp.