Appointed by Joseph Stalin, Yagoda supervised arrests, show trials, and executions of the Old Bolsheviks Lev Kamenev and Grigory Zinoviev, climactic events of the Great Purge.

The son of a jeweller, trained as a statistician, who worked as a pharmacist's assistant,[3] he claimed that he was an active revolutionary from the age of 14 when he worked as a compositor on an underground printing press in Nizhny Novgorod, and that at the age of 15 he was a member of a fighting squad in the Sormovo district of Nizhny Novgorod, during the violent suppression of the 1905 revolution.

An American journalist who was allowed to join them on the trip described Yagoda as "a spare, slightly-tanned, trim looking, youngish officer" adding that it was "difficult to associate terror with the affable and modest person".

[7] By contrast, the chemist Vladimir Ipatieff met Yagoda briefly in Moscow in 1918 and later recorded that he had thought that "it was unusual for a young man in his early twenties to be so unpleasant.

[9] When Stalin ordered that the Soviet Union's entire rural population were to be forced onto collective farms, Yagoda is reputed to have sympathised with Bukharin and Rykov, his opponents on the right of the communist party.

In the contemptuous opinion of Bukharin's widow, Anna Larina, Yagoda "traded his personal views for the sake of his career" and degenerated into a "criminal" and a "miserable coward".

[12] As deputy head of the OGPU, Yagoda organized construction of the White Sea–Baltic Canal using forced labor at breakneck speed between 1931 and 1933, though at the cost of huge casualties.

"Whenever Gorky met Stalin or other members of the Politburo, Yagoda would visit Kryuchkov's flat afterward, demanding a full account of what had been said.

"[18] He had developed an obsession with Max Peshkov's wife, Timosha, and visited her daily when she was newly widowed, though her mother denied that they were ever lovers.

[20] On 10 July 1934, two months after Menzhinsky's death, Joseph Stalin appointed Yagoda People's Commissar for Internal Affairs, a position that included oversight of both the regular and the secret police, the NKVD.

At some point, it was discovered by the NKVD that a conspiratorial Opposition Bloc had been formed in 1932, by Leon Trotsky and various other Soviet politicians like Lev Kamenev and Grigory Zinoviev.

[21] Yagoda then worked closely with Andrei Vyshinsky in organizing the first Moscow Show Trial, which resulted in prosecution and subsequent execution of Zinoviev and Kamenev in August 1936, beginning the Great Purge.

The Red Army high command was not spared and its ranks were thinned by Yagoda, as a precursor to the later and more extensive purge in the Soviet military.

More than a quarter of a million people were arrested during the 1934–1935 period; the GULAG system was vastly expanded under his stewardship, and penal labor became a major developmental resource in the Soviet economy.

In the middle of 1936, Stalin received a report from Yagoda detailing the unfavorable public reaction abroad to the show trials and the growing sympathy among the Soviet population for the executed defendants.

The report enraged Stalin, interpreting it as Yagoda's advice to stop the show trials and in particular to abandon the planned purge of Mikhail Tukhachevsky, Marshal of the Soviet Union and the former commander in chief of the Red Army.

Stalin was already unhappy with Yagoda's services, mostly due to mismanagement of Kirov's assassination and his failure to fabricate "proofs" of ties between Kamenev and Zinoviev and the Okhrana (the tsarist security organization).

And a witness reports that at just that moment a match flared in the shadows behind a window on the second floor of the hall, apparently behind a muslin curtain, and, while it lasted, the outline of a pipe could be seen.

Yagoda's father, Grigori, the jeweller, who was aged 78 in 1938, wrote directly to Stalin disowning "our only surviving son" because of "his grave crimes".

[36] Yagoda's wife was Ida Averbakh (Russian Wikipedia), one of whose uncles, Yakov Sverdlov, was a prominent Bolshevik, and another, Zinovy Peshkov, was the adopted son of the writer Maxim Gorky.