The Chicago Tylenol Murders (Illinois, 1982)

In September 1982, seven people in the Chicago area died after consuming Tylenol capsules laced with potassium cyanide. Authorities found that tainted capsules had been placed on store shelves, sparking nationwide panic and a massive product recall. The culprit was never caught, though various suspects were investigated. The tragedy led to major changes in packaging regulations (e.g., tamper-evident seals).