The “Investigation Report on the Life in a German Extermination Camp (Kz Natzweiler) and the Atrocities Committed There. 1941-1944” was in the files of the Supreme Headquarters Allied Expeditionary Force (SHAEF). As its title suggests, the report discusses what the Allies knew about the Natzweiler camp.
Click here to read the report.
Source: C.D. Jackson Papers, Box 2, Atrocities - Paris (1); NAID #12005699, Dwight D. Eisenhower Presidential Papers