Forty years ago, cyanide-laced Tylenol capsules led to the deaths of seven people all around the Chicago area. America was gripped by paranoia and fear. Why was this happening? Who would be next? Police grasped for suspects who might be the so-called “Mad Poisoner.” A crossover special from Serial Killers and Conspiracy Theories. Learn more about your ad choices. Visit podcastchoices.com/adchoices