Genrikh Grigoryevich Yagoda (born 1891, Łodz, Pol., Russian Empire—died March 15, 1938, Moscow) was the head of the Soviet secret police under Stalin from 1934 to 1936 and a central figure in the purge trials.
https://www.britannica.com/biography/Genrikh-Grigoryevich-Yagoda