In late September 1982, the Chicago area experienced a series of sudden, unexplained deaths tied to a common over-the-counter medication. On September 29 and the days immediately following, seven people died after ingesting Extra-Strength Tylenol (acetaminophen) capsules that had been contaminated with potassium cyanide. The victims included men and women of different ages and neighborhoods; investigators later linked their deaths by chemical analysis of the capsules and autopsies. The case attracted intense national attention because it represented a new kind of criminal harm: tampering with sealed consumer products on store shelves. Prior to 1982, packaging and distribution of mass-consumed medicines and food had rarely been attacked in this way. The Tylenol incidents exposed vulnerabilities in how packaged pharmaceuticals were sold and prompted immediate public-health and regulatory responses. Johnson & Johnson, the maker of Tylenol, responded by cooperating with investigators, advising consumers to stop using Tylenol products, and ultimately issuing a nationwide recall of millions of bottles. Retailers pulled Tylenol from shelves, and consumers were warned through news media. The company later reintroduced Tylenol in tamper-evident packaging—blister packs and sealed bottles with glued caps and foil seals—measures that quickly became industry standards. Law enforcement conducted a lengthy investigation led by local, state and federal agencies, including the FBI. Investigators pursued multiple leads and suspects over the years. Despite extensive inquiries, including examinations of store surveillance, interviews, chemical forensics and public tips, no one has been definitively convicted for the poisonings. Some suspects were publicly named and later cleared or remained persons of interest; others were investigated but no case met the burden for prosecution. As a result, the identity and motive of the perpetrator or perpetrators remain unresolved in public records. The poisonings had immediate and lasting impacts. Regulators and manufacturers re-evaluated packaging and product safety standards; the Food and Drug Administration and industry groups promoted tamper-resistant and tamper-evident packaging. Retail practices changed—pharmacies and stores altered shelf stocking and security procedures. Public awareness of product safety rose sharply, and the phrase “product tampering” entered common usage in discussions of consumer risk and criminality. The Chicago Tylenol poisonings also prompted changes in crisis communication. Johnson & Johnson’s swift recall and public messaging are often cited in case studies for corporate crisis response, though the event also highlighted limitations in emergency tracing and prevention when crimes target widely distributed consumer goods. Because key investigative details and some leads remain unresolved, aspects of the case have generated speculation and numerous later theories. Reliable, contemporary sources—news reports, court records, and official investigative statements—document the deaths, the laboratory confirmation of cyanide in capsules, the nationwide recall, and the subsequent packaging changes. However, claims about a named perpetrator, motive, or a definitive investigative breakthrough are not supported by public court convictions; any such claims should be treated as unproven. The 1982 Tylenol poisonings stand as a watershed moment in U.S. consumer safety history: a rare criminal misuse of packaged medicine that exposed systemic vulnerabilities, led to industry-wide packaging reforms, and left unresolved questions about who was responsible for the deaths.