Hinterkaifeck murders

The Hinterkaifeck murders occurred on the evening of March 31, 1922, in which six inhabitants of a small Bavarian farmstead, located approximately 70 kilometres north of Munich, Germany, were murdered by an unknown assailant. The six victims were Andreas Gruber and Cäzilia Gruber; their widowed daughter Viktoria Gabriel; Viktoria's children, Cäzilia and Josef; and the maid, Maria Baumgartner. They were found struck dead. The perpetrator lived with the six corpses of their victims for three days. The murders are considered one of the most gruesome and puzzling unsolved crimes in German history.

Four of the dead bodies were stacked up in the barn, the victims having been lured into the barn one by one. Prior to the incident, the family and their previous maid reported hearing horrible sounds coming from the attic, which led to that maid quitting. This case remains unsolved to this day.

Source: Wikipedia