On a warm June afternoon in 1868, a 24-year-old woman accepted a glass of lemonade from her nurse at a Geneva boarding house. Within moments, her pupils dilated grotesquely, her heart pounded violently, and reality dissolved into nightmare. That glass of lemonade broke open one of Switzerland's most disturbing criminal cases.SEASON & EPISODE CONTEXTThis is Episode 9 of Foul Play Season 36: "Serial Killers in History," examining murderers from ancient times through the early 1900s. This season explores 15 cases spanning centuries and continents, revealing how serial murder predates modern criminology by millennia.THE CASE SUMMARYBetween 1865 and 1868, Marie Jeanneret worked as a private nurse in Geneva and surrounding areas of Switzerland, moving between respectable boarding houses and private hospitals. Everywhere she went, patients died under mysterious circumstances. Eleven-year-old children. Elderly widows. Entire families.Her method was both calculated and cruel. She used cutting-edge poisons for the 1860s—plant alkaloids like atropine from belladonna and morphine from opium poppies. These substances were so difficult to detect in corpses that she might never have been caught. She offered candy she called "princesses" to children. She served sweetened water to friends. She predicted deaths days before they happened—not because she had medical insight, but because she knew exactly when the poison would finish its work.When authorities finally exhumed the bodies in 1868, they found chemical signatures of murder in decomposing tissue. The trial revealed at least six confirmed murders and perhaps thirty attempted murders. But the verdict the jury reached would create one of criminal history's most profound paradoxes—her case helped abolish the death penalty in Geneva three years later.THE VICTIMSMarie Jeanneret's victims weren't random—they were people who trusted her completely during their most vulnerable moments:Marie Grétillat, 61, hired Jeanneret for what should have been a minor illness. She died in February 1867 after weeks of escalating agony.Sophie Juvet, 58, died in September 1867 at the Maison de Santé hospital where Jeanneret worked as a nurse.Jenny-Julie Juvet, Sophie's daughter, was only 11 years old. She loved candy and trusted the nurse who brought her special bonbons called "princesses." Before she died in January 1868, she begged her family not to let the nurse near her anymore. They thought she was delirious. She wasn't—she knew.Auguste Perrod (around 80), Louise-Marie Lenoir (72), Madame Hahn, Demoiselle Gay, Demoiselle Junod, Julie Bouvier, and Jacques Gros (Julie's father) all died under Jeanneret's care between 1867 and 1868.KEY CASE DETAILSTHE METHOD: Jeanneret used belladonna (deadly nightshade) and morphine as her primary weapons. Belladonna poisoning produces distinctive symptoms: grotesquely dilated pupils, rapid heartbeat, extreme light sensitivity, terrifying hallucinations, and eventually seizures and respiratory failure. Morphine suppresses breathing until victims simply stop inhaling—the death looks peaceful but is actually suffocation.As a nurse, she had legitimate access to these substances and professional cover for every action. She mixed poisons into sweet items—lemonade, sweetened water, candy—because sugar masks the bitter taste effectively. For some victims, she administered lower doses over time, creating slow declines that mimicked natural illness. For others, she used massive doses intended to kill quickly.THE BREAKTHROUGH: The case broke open when Marie-Catherine Fritzgès, 24, survived a belladonna poisoning in June 1868. Her doctor recognized the symptoms immediately and contacted authorities. Police searched Jeanneret's rooms and found bottles of belladonna extract, containers of morphine, and detailed nursing notes documenting every symptom, decline, and death—inadvertently documenting her own crimes.HISTORICAL CONTEXT & SOURCESThe 1860s represented a turning point in forensic medicine. Swiss medical examiners used groundbreaking techniques to test tissue samples for alkaloid compounds in exhumed bodies—finding chemical signatures consistent with belladonna and morphine poisoning. This case marked one of the first instances where forensic medicine played a crucial role in securing a conviction in Switzerland.The trial opened in Geneva in late 1868 with overwhelming evidence: poisoned bodies, survivors' testimony, bottles of poison, and Jeanneret's own nursing notes. On November 19, 1868, the jury returned a stunning verdict—guilty on all counts, but they recommended clemency. Instead of execution, Jeanneret received life imprisonment with hard labor.Three years later, in 1871, the Canton of Geneva abolished the death penalty. Jeanneret's case was cited as a key example—a jury had looked at overwhelming evidence of serial murder and chosen mercy over execution.RESOURCES & FURTHER READINGSwiss criminal history archives maintain extensive records of t