Mary Clement.

About Mary Clement

Marie "Mary" Clement, also known under several aliases, was a Luxembourgish-born American serial killer who poisoned her parents and two of her sisters at their home in Dubuque, Iowa. Although never charged in their deaths on the grounds that she was insane at the time, she was later convicted of attempting to poison her sister's family in Rose Hill, Illinois and sentenced to a year in the Joliet Prison.