Marsh is the director of experimental sciences for AbbVie (formerly Abbott Laboratories) in Lake Forest, Illinois. She received M.S. and Ph.D. degrees in pharmaceutical chemistry from the University of Kansas. Marsh has published more than 250 scholarly articles in scientific journals and holds nearly 50 patents. She works at the interface between discovery and development, helping move new compounds through animal studies and into clinical trials. Most recently, she has been working on a project to provide a single-dose cure to malaria. She is a recipient of the Hollins Distinguished Alumnae Award.