In the autumn of 1791, Mozart lay dying. He was convinced he had been poisoned. Not by a rival, not by an enemy soldier — but by a liquid so subtle, so invisible, that no doctor in Europe could detect it. He called it by its name: Acqua Tofana.

He was afraid of a dead woman.

The story begins in Palermo, Sicily, around 1630. A woman named Giulia Tofana — possibly the daughter of Thofania d’Adamo, who had been executed in 1633 for poisoning her own husband — began producing and selling a liquid that would become one of the most feared substances in early modern Europe.

The poison itself was almost insultingly simple to look at. Colorless. Odorless. Tasteless. Four to six drops was enough to kill the strongest man. Its base ingredient was arsenic, likely combined with belladonna and lead. It left no trace a 17th-century physician could identify.

But here is the part that makes this story different from ordinary poisoning cases.

Giulia Tofana was not selling to criminals. She was selling to wives.

Italy in the 1600s gave women almost no legal exit from a bad marriage. Divorce was forbidden. Abuse was rarely prosecuted. A woman who married the wrong man was, in the eyes of the law, simply stuck. So Tofana built a different kind of business. She marketed Acqua Tofana as a cosmetic product — a healing water, a beauty elixir — something a woman could display openly on her vanity table without suspicion. Sometimes it was disguised as the “Manna of St. Nicholas,” a popular religious cure-all. The poison sat in plain sight.

Her network operated for decades. She worked with her daughter, Girolama Spana, and a circle of female associates. Clients would come seeking help. They would leave with a small vial and instructions. The poison worked slowly — a few drops added to food or drink over days or weeks, mimicking natural illness so precisely that no one asked hard questions.

By the time authorities began unraveling the operation in Rome in 1659, the numbers were staggering. Tofana herself reportedly confessed to 600 deaths in Rome alone between 1633 and 1651. Historians dispute the exact figure, but the Spana network — the organization that carried on after Tofana — was real, documented, and deadly. In July 1659, five women were sentenced to death by hanging in Rome’s Campo dei Fiori. A sixth, who had fled to Naples, was captured and executed in March 1660.

Giulia Tofana herself reportedly died in Rome around 1651, before the full crackdown. She never faced the scaffold.

The recipe for Acqua Tofana was never officially recorded. What survived was the legend — potent enough that 140 years after Tofana’s death, a dying Mozart whispered her name in fear.

History tends to remember poisoners as monsters. But the women who bought Acqua Tofana were not, by any account, acting out of cruelty. They were acting out of desperation — in a world that had decided their suffering didn’t matter. The poison was terrible. The system that created the demand for it was worse.