Kurt Gerstein was a German SS officer and head of technical disinfection services of the Hygiene-Institut der Waffen-SS. After witnessing mass murders in the Belzec and Treblinka Nazi extermination camps, Gerstein gave a detailed report to Swedish diplomat Göran von Otter, as well as to Swiss diplomats, members of the Roman Catholic Church with contacts to Pope Pius XII, and to the Dutch government-in-exile, in an effort to inform the international community about the Holocaust as it was happening. In 1945, following his surrender, he wrote the Gerstein Report covering his experience of the Holocaust. He died of an alleged suicide while in French custody.

Belzec was a Nazi German extermination camp in occupied Poland. It was built by the SS for the purpose of implementing the secretive Operation Reinhard, the plan to murder all Polish Jews, a major part of the "Final Solution", the overall Nazi effort to complete the genocide of all European Jews. Before Germany's defeat put an end to this project more than six million Jews had been murdered in the Holocaust. The camp operated from 17 March 1942 to the end of June 1943. It was situated about 500 m (1,600 ft) south of the local railroad station of Bełżec, in the new Lublin District of the General Government territory of German-occupied Poland. The burning of exhumed corpses on five open-air grids and bone crushing continued until March 1943.