From Shadow Unit Wiki
Age: probably 48 or 49 
Dr. Madeline Frost comes from an abusive family with a history of mental illness. Her father killed her mother, although we do not yet know how or when.  At the age of sixteen, she survived a car accident which her father did not.
Frost is the "on-call forensic specialist" for the ACTF. She is not an agent, but an oncological pathologist at Johns Hopkins Medical Center. She is middle-aged, short and small-boned, especially her hands. Daniel Brady describes her at one point as "dumpy."
She does not have a cell phone for herself, though she has two she uses for work--one for the BAU and one for the hospital. She does not want people to call her to chat. She is extremely precise in her speech, and uses a minimum of pleasantries for social purposes. She will say "You're welcome" in response to "thank you," because that is what one says.
Her belief is that "patients are fine, as long as they arrive in pieces," though she is present when gamma Melinda Grossman shoots herself. At that scene, Frost makes a heroic effort to save the girl, an effort only she herself considers incompetent.
Her time sense is accurate "to the second." 
Hafidha Gates actively dislikes her.