In today's world, homicide detectives are expected to be jacks-of-all-trades: equally adept at chasing outlaws and identifying DNA evidence at the scene of the crime. But, in an overwhelmingly male-dominated field, Frances Glessner Lee, a Midwestern woman without a high school diploma, made contributions throughout the 1930s and 40s that earned her the moniker 'The Mother of Forensic Science.'

A&E True Crime talks to real bloodstain pattern analysts about how the science works and why some people, including those in the BPA field, are skeptical about how it's used in criminal cases.