This story previously aired on June 10, 2023. These are the words of Mark Twitchell, written to investigative journalist and author Steve Lillibuen: Steve Lillibuen [reading letters]: “It would appear that I’m unique in the world. There is no key. No root cause … If I really were capable of premeditated murder … Normal, healthy, well-adjusted 30-year-old men … I once heard the...