In 1982, seven people in the Chicago area died after taking Tylenol capsules laced with cyanide in what became one of the most notorious unsolved crimes in U.S. history. The random and terrifying nature of the poisonings caused nationwide panic, led to one of the largest product recalls in history, and forever changed the way over-the-counter medications are packaged and sold. Despite decades of investigation, the person responsible was never brought to justice.