From Halopedia, the Halo wiki
Office of Naval Intelligence
Cynthia Diggs is a human scientist affiliated with the Office of Naval Intelligence.
During the Human-Covenant War Diggs worked for the UNSC, helping reverse-engineer Covenant technology so the UNSC could get a better understanding of how they functioned.
She is the wife of Bob Casper, the manager of the Zeta Halo project.