<P> After 1930, open criticism of Stalin within the Communist Party was virtually non-existent, though Stalin continued to hunt for discreet dissenters . Stalin dominated the Politburo (the executive branch of the Soviet government) through staunch allies such as Sergo Ordzhonikidze, Lazar Kaganovich, Vyacheslav Molotov, and Kliment Voroshilov . </P> <P> On the night of 9 November 1932, Stalin's wife, Nadezhda Alliluyeva, shot herself in her bedroom . Stalin was sleeping in another room that night, so her death was not discovered until the next morning . To prevent a scandal, Pravda reported the cause of death as appendicitis . Stalin did not tell his own children the truth to prevent them from spreading the truth accidentally . </P> <P> On 1 December 1934, Sergei Kirov was murdered by Leonid Nikolaev . The death of this popular, high - profile politician shocked Russia, and Stalin used this murder to begin The Great Terror . Within hours of Kirov's death, Stalin declared Grigory Zinoviev and his supporters to be responsible for Kirov's murder . Lev Kamenev and Grigory Zinoviev were arrested and, to escape long prison sentences, confessed to political and moral responsibility for Kirov's murder . In January 1935, Zinoviev was sentenced to 10 years imprisonment, and Kamenev was sentenced to 5 years imprisonment . Stalin sanctioned the formation of troikas for the purpose of extrajudicial punishment . In April 1935, Kamenev's prison sentence was increased by another 5 years, to a total of 10 years imprisonment . Hundreds of oppositionists linked to Kamenev and Zinoviev were arrested and exiled to Siberia . In late 1935, Stalin reopened the case . Kamenev and Zinoviev were interrogated again, and the exiled Trotsky was now accused of being the leading mastermind in Kirov's murder . In July 1936, Stalin promised Kamenev and Zinoviev (through NKVD chief, Genrikh Yagoda) that there would be no executions or persecution of their families if they confessed to conspiring with Trotsky . Stalin's promise was soon broken . A few weeks later, after a show trial, Kamenev and Zinoviev were both executed on 25 August 1936 . </P> <P> Spearheading Stalin's purges was a Commissar called Nikolai Yezhov, a fervent Stalinist and a believer in violent repression . Nikolai Yezhov continued to expand the lists of suspects to include all the old oppositionists as well as entire nationalities, such as the Poles . </P>

Who ruled the soviet union with sole power in a regime of terror