Baba Anujka

A serial killer named Baba Anujka from Serbia is believed to have killed as many as 150 people using poison during the 19th and 20th centuries. She was apprehended in 1928 at the age of 90 and sentenced to 15 years in prison in 1929 as an accomplice in two murders. She was released due to old age after spending eight years in prison.