Where can I find a Prisoner of War Roster for German and Italian Prisoners who were imprisoned at POW Camp Douglas in Douglas, WY from 1943-1946?

I am the Curator for the POW Camp Douglas Officers' Club State Historic Site in Douglas, WY.  This POW Camp housed German and Italian POW's from 1943-1946.  The officers' club is the only remaining building.  On the walls of the Officers' Club three Italian POW's painted murals depicting Western United States Cowboy Culture and Landscapes. We have numerous archival documents about this POW Camp, however, we do not have a roster of names of the German and Italian men that were imprisoned here.  I have searched National Archives, our State Archives and have not found anything.  Where can I search for these records?  We know that the prisoners came from the African Theatre to a New York port and then by train to Cheyenne, WY (Ft. Warren) and another train up to Douglas, WY.  Any suggestions would be appreciated.