 However, it had already been agreed that Wilmersdorf would be administered as part of the British sector, and in July the Red army troops withdrew to the pre-agreed frontiers, leaving the British to take control in this part of Berlin.British military police arrested Gerstner on 24 July 1945, reasoning that since he had worked at the German embassy in Paris he must have been a senior Nazi official.They handed him over to the Soviet sector to be detained pending further decisions.