On September 29, 1982, 12 year old Mary Kellerman took a Tylenol capsule for a cold and died within hours. Within two days six more people in the Chicago area died the same way, including three members of a single family, the Januses, who had unknowingly shared capsules from the same tainted batch.
Someone had opened bottles on store shelves, replaced the medicine inside with potassium cyanide, and resealed them for unsuspecting buyers to find. No poisoner was ever caught. A man named James W. Lewis was convicted of extortion after writing to the manufacturer claiming responsibility and demanding a million dollars to stop the deaths, but he later insisted the letter was a bluff, and investigators could never tie him to the actual killings.
The case remains unsolved to this day, but it changed how medicine is sold worldwide, ending loose powder capsules and ushering in the tamper proof seals now standard on every bottle.
