In July 1927, Frinovsky was again transferred to Moscow, this time as aide to the commander of the Special Section for the region. In 1927, he completed high-command courses at the Frunze Military Academy. From 28 November 1928 until 1 September 1930 he served as the commissar of the Special Forces division assigned to the Dzerjinsky College of the OGPU USSR. On 1 September 1930 Mikhail Frinovsky was promoted and made chairman of the GPU of Azerbaijan. In April 1933, he was again promoted and became the commander of OGPU Border Guard. On 10 July 1934 Frinovsky became head of Border and Internal Troops for the NKVD. Great Purges Frinovsky was one of the major beneficiaries of the first purge of the NKVD that followed dismissal of its head, Genrikh Yagoda. He had had some kind of falling out with Yagoda, but was on good terms with Nikolai Yezhov, Yagoda's successor. On 16 October 1936 Frinovsky was appointed Deputy Chairman of the NKVD, which made him third in seniority within the security apparatus at the start of the great purge. On 15 April 1937 he was promoted First Deputy Chairman of the NKVD, and head of the Chief Directorate of State Security. Now second in command to Yezhov, he was in charge of the interrogation of Yagoda, in which Stalin took a personal interest. He was jointly responsible with Yezhov for setting the quotas of arrests that were required in each part of the Soviet Union, and in drawing up the 383 lists submitted for Stalin's approval, containing 44,000 names of people who were to be arrested, of whom 39,000 were to be executed. He led the squad of senior NKVD officers who descended on Kiev on 7 June 1937 to facilitate arrest of the recently dismissed head of the Ukraine NKVD, Vsevolod Balitsky, and of Red Army officers suspected of being too closely linked to their former commander, Iona Yakir. On 17 February 1938 he supervised the murder of the head of the NKVD Foreign Department, Abram Slutsky, who was chloroformed and injected with lethal poison in Frinovsky's office. On 28 April 1938 he signed the warrant for the second arrest of the poet Osip Mandelstam, who died in the gulag. On 17 June 1938 he arrived in Khabarovsk, in the Far East, in a special train carrying a large contingent of NKVD officers, to supervise mass arrests of