On or around October 5, 1982, a series of deaths in the Chicago area revealed that Tylenol (acetaminophen) capsules had been tampered with and deliberately contaminated with potassium cyanide. The first widely reported fatality occurred in late September and by early October authorities had linked seven deaths to ingestion of the adulterated capsules. Victims included men and women from different neighborhoods and age groups, heightening public alarm. Local police, the Cook County medical examiner, and the Food and Drug Administration (FDA) quickly launched investigations. Officials determined that the poison had been introduced after the product left the manufacturing facility, likely at the retail level, because tampering was not consistent with contamination at the source. The investigation involved extensive interviews, laboratory analysis of recovered bottles and capsules, and coordination with other law enforcement agencies as authorities sought to determine how and where the cyanide had been introduced and whether a single perpetrator or multiple actors were involved. Johnson & Johnson, the parent company of the product’s maker, McNeil Consumer Products, acted rapidly after the deaths and media coverage intensified. The company issued a nationwide recall of Tylenol capsules and advised consumers not to use capsule products, a rare and consequential step that drew attention to corporate responsibility during a public-health crisis. Retailers removed Tylenol from their shelves, and many pharmacies and stores temporarily closed or restricted access to over-the-counter medications while authorities investigated. The case became a national story because of its implications for product safety and the apparent randomness of the attacks. Consumers reacted with fear and confusion; sales of over-the-counter pain relievers dropped sharply and many people shifted from capsules to tablets or stopped using the brand. Media coverage highlighted both the human toll and the difficulty of policing packaged consumer goods once they reached retail outlets. Although investigators pursued multiple leads, including reports of suspicious behavior and potential suspects, the case remained officially unsolved for many years. There were arrests and investigations over time, and various theories emerged, but no perpetrator was definitively convicted in connection with the Chicago-area poisonings. The unresolved nature of the case left lingering questions about motive and method. One lasting consequence of the events was a major change in how over-the-counter medications were packaged and sold. The Tylenol poisonings prompted manufacturers and regulators to adopt tamper-evident and tamper-resistant packaging widely across the industry. Innovations included sealed blister packs, glued boxes, and plastic wrap or other visible seals designed to make unauthorized opening evident to consumers. The FDA and Congress also moved to strengthen regulations related to consumer product packaging and to develop federal anti-tampering statutes. Corporate crisis response and public relations practices were also affected. Johnson & Johnson’s swift recall and public statements are frequently cited in business and crisis-management literature as a case study in rapid corporate action to protect public safety and brand trust, though analyses also note challenges the company faced in communicating during a fast-moving investigation. The Chicago Tylenol poisonings remain a key episode in U.S. public-health and consumer-safety history. The fatalities and the subsequent regulatory and industry changes altered how medicines are packaged and sold, and they continue to be referenced in discussions of product security, crisis management, and unresolved criminal investigations.