Mark Twitchell was an aspiring filmmaker who wrote screenplays about murder and compared himself to TV's fictional serial killer, Dexter Morgan. In 2008, police were investigating the disappearance of 38-year-old John Altinger and discovered Twitchell's garage where he had just filmed his latest project about a serial killer. “48 Hours" Correspondent Troy Roberts reports. This classic "48 Hours" episode last aired on 7/10/2012. Watch all-new episodes of “48 Hours” on Saturdays, and stream on demand on Paramount+. To learn more about listener data and our privacy practices visit: https://www.audacyinc.com/privacy-policy Learn more about your ad choices. Visit https://podcastchoices.com/adchoices