Helena Kraft (sp?) was. Lake Zoar in Connecticut. Her husband (ex?) did a really thorough job, took several mistrials to convict him.
http://en.wikipedia.org/wiki/Murder_of_Helle_Crafts#In_popular_culture
Hah! I didn’t know Fargo was inspired by real events ... and I’ll bet those Reason posters didn’t either. I still say it’s not a serious threat.