I grew up in Sandy Hook, part of Newtown.

https://en.wikipedia.org/wiki/Murder_of_Helle_Crafts

This woman's murder was the inspiration for Fargo.

The Coen Brothers have changed the explanation multiple times; the movie claims to be "exactly how it happened" (always took this as a joke), the DVD claims it was inspired in the murder you mentioned, and still in 2015 they claimed the story is completely made up...