Costello earned her degree in government from Harvard University and earned her teaching certificate and M.A. in teaching from the University of Alaska Southeast. Costello's professional experience includes working as owner of a public relations consulting business, deputy director of communications for then-Gov. Frank Murkowski, public information officer for the Media Support Center of the Office of then-Gov. Walter Hickel, teacher at Service High School and Juneau-Douglas High School, account executive for Bradley/Reid Communications, aide to then-state Rep. Norm Rokeberg, and instructor for Nine Star Education and Employment Services.
