The evidence supporting the theory that a local Mab poisoner was behind the Tylenol murders relied on the short shelf life of cyanide in gelatin capsules, which would have made it impossible for someone to have gone around Chicago lacing Tylenol bottles in one day. This evidence ultimately led to the exonerated of a suspect who had already moved to New York before the Tylenol murders took place.
The podcast discusses the possibility of the Zodiac Killer copying names and addresses of newspapers and his defense for a speculative scenario.