Eva Dugan:

On February 21, 1930, Eva Dugan was hanged for the murder of Tucson
chicken Rancher Andrew J. Mathis. She was the only woman ever executed
in Arizona, and her hanging brought the state national notoriety,
largely because they accidentally yanked her head off.
More -- 
http://www.adc.state.az.us/DeathRow/Data6.htm

She's the only woman executed in Arizona.

  Feb 21 1930 Eva Dugan, hung and beheaded [accidentally] for the murder 
  of chicken rancher A J Mathis in Tucson Az.  Executed at Az State Pen, 
  Florence Az. 1st and last woman hung in Az because of public outcry 
  because of beheading.  A J Mathis was my gg grandfather.  

http://ftp.rootsweb.com/pub/roots-l/messages/97sep/56414
Victim was her employer (briefly, housekeeper, let go)

http://www.geocities.com/trctl11/amfem.html