Considered a primary suspect in the unsolved Jack the Ripper murders, Polish-born Severin Antoniovich Klosowski also gained considerable notoriety as "The Borough Poisoner of Southwark" in the late 1800s. Within a span of five years, Klosowski took on three women as his wives and lethally poisoned each with deadly doses of antimony. This study of Klosowski's murders of Mary Spink, Elizabeth "Bessie" Taylor and Maud Marsh includes extensive accounts of the individual crimes, the accompanying investigations and Klosowski's conviction and execution. The final chapter examines intense police and media speculation that Klosowski may also have been the unidentified serial killer Jack the Ripper, citing period news articles and more recent developments in the notorious case. One appendix provides a detailed timeline of Klosowski's "poison period" from 1892 to 1903.