given to the US Holocaust Memorial Museum in 2007 by a US Army intelligence officer who discovered it in Germany in 1945 and kept it over 60 years. Strange he didn't provide this documentation to US authorities immediately given its importance and historic value.
The Höcker Album (or Hoecker Album) is a collection of photographs believed to have been collected by Karl-Friedrich Höcker, an officer for the SS during the Nazi regime in Germany. It contains over one hundred images of the lives and living conditions of the officers and administrators who ran the Auschwitz-Birkenau concentration camp complex. The album is unique, and an indispensable document of the Holocaust; it is now in the archives of the United States Holocaust Memorial Museum (USHMM) in Washington, D.C.
Discovery: According to the museum, the photograph album was found by an unidentified American counterintelligence officer who was billeted in Frankfurt after Germany's surrender in 1945. This officer discovered the photo album in an apartment there, and when he returned to the United States, he took the album with him.[1]
In January 2007, the American officer donated the album to the USHMM, with the request that his identity not be disclosed. The captions of the photographs, and the people featured in the images, quickly confirmed that it depicts life in and around the Auschwitz camps. The very first photograph is a double portrait of Richard Baer, Auschwitz camp commandant between 1944 and 1945, and Baer's adjutant, Karl Höcker.[2]
More, https://en.wikipedia.org/wiki/H%C3%B6cker_Album