10 Horrifying Serial Killers You've Never Heard Of
5. The Saltychikha

Darya Nikolayevna Saltykova, commonly known as the Saltychikha, was a Russian noblewoman and sadist and serial killer, infamous for torturing and murdering over a hundred people in the mid seventeenth century, mostly women and young girls.
Widowed before the age of thirty, she inherited a huge estate where she lived with her sons. Well-connected, she managed to avoid being investigated (despite the large numbers of commoners missing from her lands) for over a decade, until relatives of the murdered women managed to place a petition before the Empress, who elected to try Saltykova publicly in order to demonstrate her impartiality.
It took the authorities six years to fully investigate the matter: 138 suspicious deaths were found to have occurred on her estates, the majority of which were considered by have been caused by the Saltychikha. She was found guilty of personally torturing thirty-eight women to death, but the death penalty had been abolished a decade earlier, and the Empress was well aware of the effect that a drastic punishment would have on her support with the Russian nobility, regardless of the nature of Saltykova's crimes.
In 1768, the Saltychikha was clapped in irons and displayed on a platform in Moscow for a single hour, with a sign around her neck saying, "This woman has tortured and murdered." After this small humiliation, she was imprisoned for life in the basement of a convent in Moscow, out of the public eye.