Gerhardt is an imprinted personality used by the Active named Sierra during an engagement at the behest of the L.A. Dollhouse. Gerhardt was a forensic analyst with the FBI sent to Tucson, Arizona to examine a body connected to the Dollhouse. Gerhardt's skills were enough to allow her to quickly determine that the individual killed as not in fact done so in Tucson, but done so somewhere else and dumped there.
Gerhardt proves to be a smart, determined forensic specialist as demonstrated by her first words after being imprinted into Sierra is a list of all the factors that contribute to the decomposition of a corpse after death. Gerhardt also is the first to notice that the body of Stephen is not actually that of a homeless person, stating that he smells like "garbage over a layer of clean skin" and "yesterday's breakfast, not last week's".