On 17 February 1943, the Higher SS and Police Leader East Friedrich-Wilhelm Krüger forwarded to the Reichsführer-SS Heinrich Himmler correspondence of German officials in the General Gouvernement (BArch NS 19/1210).
The cause was a letter written by Wilhelm Hagen, the medical officer of Warsaw, to Adolf Hitler. In his letter of 7 December 1942, Hagen explained that Lothar Weirauch, head of the Department of Population and Welfare, had revealed that "it is intended or
considered, in the course of the resettlement of 200,000 Poles in the east
of the General Government...to deal with a
third of the Poles - with 70,000 old people and children under the age
of 10 - as with the Jews, that is, to kill them" (see document below). He requested Hitler for his intervention and decision on the issue.