In May 1937, Berman was appointed head of the NKVD in Belorussia (Belarus). In this role, he is said to have been the first official to order his staff to use torture, and was "sadistic even by NKVD standards". His victims included a group of former high ranking communists, writers and poets, executed on 29–30 October 1937. In January 1938, he reported at a conference of regional NKVD chiefs that his staff had arrested 60,000 people over the previous eight months. Berman's mass killings in Belarus purposefully targeted the educated elite and representatives of Belarusian culture. Simultaneously, Berman supervised the Polish Operation of the NKVD in Belarus, in which over seventeen thousand people were sentenced to death, most of them Poles. Many of Berman's mass executions were large scale, and were carried out at the Kurapaty mass killing site.