Plot Synopsis

Using re-enactments and key insights and analysis from forensic psychologists, psychiatrists, and criminal profilers, DIABOLICAL explores the psychological workings of murderers, who are all seemingly kind-hearted people with a looming dark side. Each 60-minute episode chronicles the tale of a different person, including: 49-year-old Neal Jacobson, who was found covered in blood by a Florida roadside, claiming that he just killed his entire family; Christine Billis, whose car veered off the road and rammed into a tree, killing her husband, Charles -- but was it a tragic accident or the result of a pre-meditated plan; and David Messenger, who brutally murdered his pregnant wife, Heather, in front of their 5-year-old son. Investigation Discovery aired all three episodes on the same night, Wednesday, December 17, 2013 from 8-11pm ET/PT.