Unsolved Mysteries S01E03 - House of Terror

In April 2011, French police discovered the wife and four children of Count Xavier Dupont de Ligonnès buried under the back porch of their home in Nantes. Xavier, the family patriarch, was not among the dead and nowhere to be found. Investigators gradually pieced together clues and a timeline that pointed to Xavier as a devious, pre-meditate killer. For instance, they now know that shortly before the crimes occurred, Xavier inherited a gun that was the same model as the murder weapon.