On January 30, 1937, the second of Stalin's purge trials occurred; Pyatakov and 16 others were sentenced to death. From the article:
"The Great Purge, also known as the Great Terror, marks a period of extreme persecution and oppression in the Soviet Union during the late 1930s. While previous purges under Stalin involved the persecutions of kulaks (wealthy peasants), Nepmen (people who engaged in private enterprise during the New Economic Policy of the 1920s), clergymen, and former oppositionists, the Great Purge is characterized by imprisonments and executions not only of these usual suspects but of Communists leaders and party members, members of the Red Army, and the Intelligentsia in great numbers. The Great Purge instituted a new type of terror in which the boundaries of those oppressed were practically nonexistent – any stain on the record, including mere association with a perceived enemy, brought one under suspicion of the NKVD, the Soviet secret police. So-called enemies of the people were charged with treason, wrecking, espionage and more. There were strong anti-elitist attitudes and persecution against those who practiced favoritism, bullied subordinates, developed their own “cults of personality,” and inappropriately used state funds.
The Great Purge began with the assassination of Sergei Kirov, whose 1935 murder by Leonid Nikolayev is suspected to have been ordered by Stalin. Kirov, though a faithful Communist, had a certain popularity in the party that threatened Stalin’s consolidation of power. Kirov’s death triggered three important, widely publicized show trials of prominent former Bolsheviks in Moscow and ultimately fostered the climate of terror during the Great Purge. The party began purging itself of undesirables as tension and suspicion mounted rapidly. It has since been determined that Denunciation of enemies was encouraged and surveillance was tightened. Hundreds of thousands were executed or died in Gulag during this period of oppression. In the summer of 1938 Nikoli Yezhov was released as head of the NKVD as the excesses of the Purge were being realized and coming to an end, but many in Gulag were not released until the end of Stalin’s leadership."