Col Shea enlisted in the Marine Corps in January 1985. Trained as a ground support equipment mechanic, she was stationed at Headquarters and Maintenance Squadron 32, 2d Marine Aircraft Wing at Marine Corps Air Station Cherry Point, NC. Subsequently, she attended the Naval Academy Preparatory School and graduated from the United States Naval Academy in 1991 with a Bachelor of Science in History.
Upon commissioning as a second lieutenant, she graduated from the Basic Communications Officer Course as an honor graduate and then served as a platoon commander and company commander with 2d Force Service Support Group in Camp Lejeune, NC. During this tour, she deployed in support of Operation SEA SIGNAL in Guantanamo Bay, Cuba. As a captain, she was assigned to Marine Corps Recruit Depot, Parris Island, SC, as a series commander and company commander with 4th Recruit Training Battalion and as the Assistant Director of the Drill Instructor School. Subsequent to this tour, she graduated as an honor graduate from Amphibious Warfare School. She was then assigned to Marine Wing Communications Squadron-38, 3d Marine Aircraft Wing at Marine Corps Air Station Miramar, CA as company commander and operations officer.
In 2001, Major Shea was selected as a White House Fellow and, in the wake of the Sept 11 terrorist attacks, served as a Special Assistant to the President's Advisor on Homeland Security. After her fellowship, she was assigned as a Strategic Analyst in Headquarters Marine Corps' Strategic Initiatives Group. In 2004, Major Shea was assigned to the 22d Marine Expeditionary Unit (Special Operations Capable) as its Communications Officer and deployed to Afghanistan and Iraq.
Returning to Headquarters Marine Corps in May 2006, LtCol Shea was assigned to the Transition Team for the 34th Commandant of the Marine Corps and then served as the Director of the Commandant's Staff Group. From 2008 until 2010, LtCol Shea commanded Fourth Recruit Training Battalion at the Marine Corps Recruit Depot, Parris Island, SC. In 2011, she graduated as the honor graduate from the Industrial College of the Armed Forces, National Defense University. Subsequently deployed to Kabul, Afghanistan for one year, LtCol Shea served as the Director of the Commander's Initiatives Group for the Commander, International Security Assistance Forces. In 2012, she reported to the 3d Marine Aircraft Wing at Marine Corps Air Station Miramar, CA to serve as the Assistant Chief of Staff G-6.
In June 2013, Col Shea assumed her present duties as the Deputy Commandant of Midshipmen.
Col Shea holds a Master of Science in Computer Information Systems from Boston University (2000) and a Master of Science in National Resource Strategy from ICAF (2011). Her awards include the Bronze Star; Meritorious Service Medal (third star in lieu of fourth award); the Joint Commendation Medal; Navy-Marine Corps Commendation Medal (second star in lieu of third award); Navy-Marine Corps Achievement Medal; the Outstanding Volunteer Service Medal; and the Combat Action Ribbon.