Most of the killings were arranged in a form of forced disappearances from multiple cities and towns upon the German arrival.[1] In the spring and summer of 1940, more than 30,000 Polish citizens were arrested by the Nazi authorities in German-occupied central Poland, the so-called General Government.[2] About 7,000 of them including community leaders, professors, teachers and priests (labeled as suspected of criminal activities) were subsequently massacred secretly at various locations including at the Palmiry forest complex near Palmiry.[3][4] The others were sent to German concentration camps.