Mark Twitchell was an aspiring filmmaker with a successful cult film, a wife and a young child. But he harbored a dark secret, the inexplicable desire to become a serial killer, partly inspired by the fictional character Dexter from the eponymous show. This week, Savannah explores how Mark was able to catfish two unsuspecting men from dating sites into his makeshift "kill room," which ultimately led to him murdering Johnny Altinger on October 10, 2008. Savannah also explores the many manifestos he wrote that make it clear that, had investigators not caught him, he would've certainly killed again.

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