Villisca Ax Murder House

On the night of June 9, 1912, an unknown assailant (or assailants) entered the Moore house in Villisca, Iowa, and brutally murdered its eight residents—Josiah and Sarah Moore, their four children, and two friends sleeping over—by hacking them in the face with an axe. The killer disappeared after the murder, and has to this day never been identified. Although suspects were identified, including a traveling minister and a local businessman, they were thrown out and the crime still remains unsolved.

Taken directly from the wikipedia entry at the link below.

http://en.wikipedia.org/wiki/Villisca_Axe_Murders