fierro has been a member of faculty of the department of legal medicine and pathology at medical college of virginia commonwealth university since 1973, and was a clinical professor of pathology at the university of virginia, charlottesville from 1983 to 1992 and also in 1999 to 2002. fierro served as a staff pathologist at richmond’s medical college of virginia hospitals from 1975 to 1992 and then returned to academia as a professor of pathology at east carolina school of medicine in greenville from 1992 to 1994.