Martha Ann Johnson

Martha had the habit of getting even with her husband after a fight 
by suffocating one of their children with her 250-pound body.  After 
four such fights they had lost four children.  Georgia.
One source says sentenced to death, another says not.
Definitely not executed...


http://www.angelfire.com/oh/yodaspage/johnson.html

http://www.unsolvedmysteries.com/usm189366.html