A native of Southern California, Arni Cook moved to Phoenix in 1991. She joined the Arizona Army National Guard in 2001 after having established a career in law enforcement for the Maricopa County Superior Court and completing graduate school in 2001. Upon enlistment, she was assigned to the 258 Engineer Company with whom she deployed to Operation Iraqi Freedom (2004-2005). She spent the ladder part of her career in the 158 Maneuver Enhancement Brigade where she served in various roles as an Engineer and Battle NCO in multiple War Fighter Exercises.

As an officer of the Court, she worked in Adult Probation supervising specialized populations including Prison Re-Entry, a position focused on helping persons being released from prison to probation assimilate to living in the community. In addition to her position as a field officer, she facilitated Thinking for a Change, cognitive behavioral intervention program to persons on Probation and served on a small team tasked with training department’s progressive initiative toward the Risk Reduction approach to community supervision to her colleagues over a two-year evolution at the Adult Probation Department. In 2020, following 19 years of military service, she retired (medically) from the Arizona Army National Guard and after 22 years of service to the community, also retired from Adult Probation.

Arni is both an Arizona State Sun Devil from the time completing her undergraduate studies and a Northern Arizona Lumberjack from obtaining her Masters of Education in Counseling and Human Relations. She is a 2018 VMLC Patriot Award recipient. She has served as a founding and Executive Member of Warrior Institute of NeuroWellness (WIN)/Horse Rhythm Foundation, a local non-profit providing Equine Therapy to Veterans and First Responders since its inception in 2011. Her spirit of service has provided the opportunity to work with other Valley and National organizations in the initiative to serve Veterans.