In the spring of 1943, the Germans finally shut down the Warsaw Ghetto by brutally suppressing the uprising which had been started by the Jewish resistance movement. Areas of the former "Jewish residential district" were transformed by the occupying forces into a "stone-brick desert". The management of the Warsaw Gestapo came to a conclusion that the ruins of the ghetto might turn out to be a convenient place to carry out secret executions of Poles – this time on a massive scale. SS-Gruppenführer Jürgen Stroop, the then SS and Police Commander (SS- und Polizeiführer) for the Warsaw district, claimed that the author of this idea was Dr Ludwig Hahn, Commander of the German security police and security service in Warsaw. While in Mokotów Prison waiting for the trial, Stroop reported on talks with Hahn to his co-prisoner from the cell, Kazimierz Moczarski.