Harold Shipman, once seen as a pillar of trust in his community, remains one of the most notorious serial killers in modern history. Over a period spanning more than two decades, he is believed to have murdered at least 215 patients, though some estimates suggest the total may have reached 250. Shipman used his position as a general practitioner to commit these crimes, exploiting the immense trust placed in him by patients, families, and colleagues alike. Central to uncovering the scale of his crimes was the rigorous application of biological evidence, particularly forensic toxicology and pathology, which ultimately exposed the patterns of murder he had meticulously concealed. This podcast explores the biology underpinning Shipman’s detection and conviction, examining how science revealed the truth behind a doctor whose professional authority had become a tool for death.