Officials began a painstaking search over "several months of investigation," according to museum director Piotr M. A. Cywiński.
"Individually verified trails were broken, people working then in the museum were no longer there," he said in a statement. "Unfortunately the author of the film has already died, the institutions which created the movie have changed, and the archives were silent. Nevertheless, we checked every lead."
Eventually they were able to make contact with the last person alive who took part in the excavation and found that the missing pieces were stored in 48 cardboard boxes at the Polish Academy of Sciences.
While Cywiński said that he "can only try to imagine why the lost objects were deposited in these boxes," he speculated the climate of anti-Semitism in Polish politics at the time might have contributed.
The items were transported to the museum last week.
More than 1.1 million people, including 900,000 Jews, were murdered by the Nazis at Auschwitz between 1940 and January 1945.