Thomas Neill Cream (27 May 1850 – 15 November 1892), also known as the Lambeth Poisoner, was a Scottish-Canadian medical doctor and serial killer who poisoned his victims with strychnine. Cream murdered up to ten people in three countries, targeting mostly lower-class women, sex workers and pregnant women seeking abortions. He was convicted and sentenced to death, and was hanged on 15 November 1892. A popular rumour, started by hangman James Billington, claims that Cream's last words were "I am Jack the...", seemingly a confession to being Jack the Ripper.
https://en.wikipedia.org/wiki/Thomas_Neill_Cream