In September 1932, Muller moved to Berlin to work with the Russian expatriate Geneticist Nikolay Timofeeff-Ressovsky, a trip intended as a limited sabbatical stretched into an eight-year, five-country journey. In Berlin, he met two physicists who would later be significant to the biology community: Niels Bohr and Max Delbrück. The Nazi movement was precipitating the rapid emigration of scientific talent from Germany, and Muller was particularly opposed to the politics of National Socialism. But the FBI was investigating Muller because of his involvement with The Spark, so he chose instead to go to the Soviet Union (an environment better suited to his political beliefs). In 1933, Muller and his wife reconciled, and she and their son David E. Muller moved with Hermann to Leningrad. There, at the Institute of Genetics, he imported the basic equipment for a Drosophila lab—including the flies—and set up shop. The Institute was moved to Moscow in 1934, and Muller and his wife were divorced in 1935.