As the war progressed, Sorge was in increasing danger but continued his service. His radio messages were enciphered with unbreakable one-time pads, which were always used by the Soviet intelligence agencies and appeared as gibberish. However, the increasing number of the mystery messages made the Japanese began to suspect that an intelligence ring was operating. Sorge was also coming under increasing suspicion in Berlin. By 1941, the Nazis had instructed SS "Standartenführer" Josef Albert Meisinger, the "Butcher of Warsaw", who was by then the Gestapo resident at the German embassy in Tokyo, to begin monitoring Sorge and his activities. Sorge was able, through one of his lovers, Margarete Harich-Schneider, a German musician living in Japan, to gain the key to Meisinger's apartment since it had once been her apartment. Much to his relief, he learned that Meisinger had concluded that the allegations that Sorge was a Soviet agent were groundless, and Sorge's loyalty was to Germany. Sorge befriended Meisinger by playing on his principal weakness, alcohol, and spent much time getting him drunk, which contributed to Meisinger's favourable evaluation of Sorge. Meisinger reported to Berlin that the friendship between Ott and Sorge "was now so close that all normal reports from attachés to Berlin became mere appendages to the overall report written by Sorge and signed by the Ambassador". The "Kempeitai", the Japanese secret police, intercepted many messages and began to close in against the German Soviet agent. Sorge's penultimate message to Moscow in October 1941 reported, "The Soviet Far East can be considered safe from Japanese attack". In his last message to Moscow, Sorge asked to be sent back to Germany, as there was no danger of a Japanese attack on the Soviet Union, and he wished to aid the Soviet war effort by providing more intelligence about the German war effort. Ozaki was arrested on 14 October 1941 and immediately interrogated. As the "Kempeitai" trailed Sorge, it discovered that Ott's wife was a regular visitor to Sorge's house and that he had spent his last night as a free man sleeping with her.