The UnXplained With William Shatner: Season 1 Episode 18Serial Killers
According to some studies, there have been more than three thousand confirmed serial killers in the United States since 1900, and criminologists believe that the US has produced more serial killers than any other country in the world. But why? What compels someone to commit cold-blooded murder again and again? And what makes an otherwise normal human being a serial killer? William Shatner investigates this disturbing phenomenon.