Colonel Mestemacher was commissioned in the U.S. Marine Corps in August 2000. Following The Basic School in 2001, she reported to 2d Force Service Support Group in Camp Lejeune, North Carolina, and served as the Battalion Adjutant and Legal Officer for 2d Maintenance Battalion. In 2003, 1st Lieutenant Mestemacher transferred to the position of Staff Secretary for 2d FSSG and deployed to Kuwait in support of Operation Iraqi Freedom. Thereafter reassigned as the Battalion Adjutant and Legal Officer for Headquarters and Service Battalion in 2004, she deployed with the battalion to Iraq in 2005.
Following her return from deployment, Captain Mestemacher reported to San Diego with the 12th Marine Corps District, Marine Corps Recruiting Command, and served as District Adjutant, Legal Officer, Family Advocacy Officer, and Equal Opportunity Officer.
Accepted into the Marine Corps Foreign Area Officer Program to study Russian, she reported to Monterey, California, in 2008 to attend the Naval Postgraduate School and the Defense Language Institute Foreign Language Center. Graduating in 2010 with a Master of Arts in Security Studies with an emphasis on Europe and Eurasia, and as Honor Graduate with a Diploma with High Honors in Russian, she reported to Kyiv, Ukraine, for a year of in-country training. During her year overseas she traveled independently throughout the Former Soviet Union, including Ukraine, Russia, Georgia, Armenia, Azerbaijan, Uzbekistan, and Kyrgyzstan.
Major Mestemacher returned to the United States in 2011 when she reported for duty as G1 Operations Officer to I Marine Expeditionary Force at Camp Pendleton, California, later also assuming a collateral duty as the I Marine Expeditionary Force Sexual Assault Response Coordinator. She was recognized as Headquarters Marine Corps Exceptional Sexual Assault Response Coordinator of the Year for 2013, then appointed as the I MEF Staff Secretary.
She reported to the HQMC International Affairs Branch for duty as the Europe and Eurasia Desk Officer in 2014, where she assisted in the planning, development, and execution of Marine Corps regional engagement events for Europe and Eurasia. As well, she prepared senior USMC leadership for European political-military and security cooperation interaction with foreign representatives.
She arrived at the Center for Advanced Operational Culture Learning, Marine Corps University, in 2015 to serve as the Regional, Culture, and Language Familiarization Officer. RCLF was a career-long education program created to instill, develop, and sustain a basic language, regional expertise, and culture capability in career Marines. Shortly following her departure from CAOCL, the American Council on Education evaluated and accredited RCLF for the first time since the program’s inception, enabling Marines to earn college credit for completing the course.
In 2017 she was assigned as Head, Senior Leader Management Branch, Manpower Management Division, HQMC Manpower and Reserve Affairs. In this capacity, she served as the USMC representative for all General Officer matters and was the process manager for the assignment, promotion, and retirement of all USMC General Officers.
Lieutenant Colonel Mestemacher served as the Commanding Officer, 4th Recruit Training Battalion, Marine Corps Recruit Depot, Parris Island, South Carolina from 2019 to 2021. Subsequently she attended the Secretary of Defense Strategic Thinkers Program, graduating with a Master of International Public Policy from Johns Hopkins University’s School of Advanced International Studies in 2022. She then served in a variety of positions within the Joint Staff J-1. She assumed command of the Marine Corps Detachment at Fort Leonard Wood in July 2024.
Colonel Mestemacher was a Fellow in the 2015-2016 class of the Massachusetts Institute of Technology program, Seminar XXI: Foreign Politics, International Relations and the National Interest. She is a 1995 graduate of Northeast Missouri State University and a 1997 graduate of Truman State University (formerly Northeast Missouri State University) in Kirksville, Missouri. A varsity swimmer for four years at NMSU, she was a team captain and Academic All-American during her junior and senior years and an All-American during her senior year. She holds a Bachelor of Arts in Music (cum laude), a Master of Arts in Piano Performance, and a Master of Arts in Music Education. Prior to joining the Marine Corps, she was a high school and middle school vocal music teacher in Monett, Missouri, and in St. Louis, Missouri. She was born and raised in St. Louis.