Complex sentence: Ząbecki, a Polish member of railway staff before the war, was one of the few non-German witnesses to see every transport that came into the camp and was present at the Treblinka station when the first Holocaust train arrived from Warsaw.
Split into simpler sentences: Ząbecki, a Polish member of railway staff before the war, was one of the few non-German witnesses to see every transport that came into the camp. Ząbecki was present at the Treblinka station when the first Holocaust train arrived from Warsaw.