In the shadowy corners of the Roman Empire, a woman named Locusta perfected the art of murder, becoming history's first documented

Season & Episode Context:

Episode 1 of 15 | Season 36: Serial Killers in History

Journey back to the 1st century AD, where we meet Locusta of Gaul—the poisoner who terrorized Rome's elite and changed criminal history forever. This season explores lesser-known serial killers spanning centuries and continents.

The Woman Behind the Poison

Locusta of Gaul was born around 20 AD in the Roman province of Gaul, a region renowned for its knowledge of herbs and natural medicines. As a young woman, she made her way to Rome and quickly established herself as an expert in creating potions and toxins. Unlike common criminals, Locusta approached murder as a refined science, maintaining detailed records of her experiments and testing compounds on slaves and animals to perfect her deadly recipes. She wasn't simply a poisoner—she was a methodical killer who built a thriving business selling her services to Rome's wealthy elite. Her reputation grew so formidable that she eventually trained others in her craft, establishing what historians consider the first school of professional poisoners. Those who knew of her work whispered her name in fear, recognizing that any suspicious death in Rome might bear her signature.

Why This Case Changed History

Locusta's crimes fundamentally reshaped how the Roman Empire approached criminal justice and public safety. Her systematic approach to murder—combined with her connections to the Imperial Court—forced authorities to confront the reality of organized, repeated killing for the first time in documented history. Following her execution in 68 AD, the Roman Senate passed the Lexi Sicarius ad Veneficis, the first comprehensive poison control legislation in recorded history. These groundbreaking reforms established formal protocols for investigating suspicious deaths, required merchants to maintain detailed records of toxic substance sales, and created harsh penalties for those who manufactured or distributed poisons. The investigation techniques developed in response to Locusta's activities laid the foundation for modern forensic toxicology and systematic criminal investigation methods that influence law enforcement to this day.

The Reign of Terror

Locusta's criminal career reached its peak when she caught the attention of Agrippina, the ambitious wife of Emperor Claudius. In 54 AD, Agrippina commissioned Locusta to create a poison that would eliminate Claudius and clear the path for Agrippina's son Nero to claim the throne. Locusta prepared a toxin that mimicked natural illness, delivering it through a dish of mushrooms—the Emperor's favorite food. When Claudius died after consuming the poisoned meal, few suspected murder, exactly as planned. Her success earned her an even more dangerous assignment: eliminating Britannicus, Claudius's legitimate son and Nero's rival for power. At a banquet, Locusta administered poison that killed the young prince within minutes, though witnesses described his death as a seizure. With Nero now Emperor, Locusta became virtually untouchable, operating openly from a luxurious villa and maintaining a client list that included senators, governors, and wealthy merchants. She employed her deadly talents so frequently that paranoia gripped Rome's upper classes—dinner parties became tense affairs, food tasters were hired at unprecedented rates, and the price of antidotes skyrocketed. Her network of trained poisoners operated throughout the Empire, creating a climate of fear that persisted for years.

Historical Context and Legacy

Ancient Rome's relationship with poison was paradoxically casual despite its deadly potential. Toxic substances were readily available from merchants and apothecaries with virtually no regulation or oversight. Locusta exploited this lax system to build her empire of death, demonstrating how easily dangerous materials could be weaponized by those with knowledge and malicious intent. When Nero died by suicide in 68 AD, Locusta's protection vanished overnight. The new Emperor Galba ordered her immediate arrest and public execution, determined to make an example of the woman who had terrorized Roman society for decades. Historical accounts suggest she was paraded through Rome's streets in chains before being subjected to prolonged torture and eventual death—some sources claim she was forced to consume one of her own poisons, while others describe her being thrown to wild animals in the arena. The reforms sparked by her crimes influenced not only Roman law but medieval European legal systems and, by extension, modern approaches to regulating dangerous substances and investigating systematic murder. Locusta's case forced authorities to grapple with questions that remain relevant today: How do we identify patterns in seemingly unrelated deaths? How do we protect society from those who kill methodically and repeatedly?

Resources & Further Reading

For those interested in learning more about ancient Roman crime and the development of criminal investigation:

• The British Museum maintains extensive collections on Roman social history, including exhibits on crime and punishment in the ancient world
• "The Poison King: The Life and Legend of Mithradates" by Adrienne Mayor explores ancient poison use and political assassination in the Roman era
• The Metropolitan Museum of Art's Roman collection includes artifacts from the Imperial period that provide context for understanding Roman society
• Academic journals such as "The Journal of Roman Studies" regularly publish research on Roman criminal justice and social history

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