Harris' Jack Crawford character was based on real-life FBI serial killer hunter John Douglas. Douglas has written several books about his career (he's essentially the founder of the FBI's BSU, and did a larger proportion of the groundwork for classifying serial killers). The two that I've read would be excellent resources for you.
Mind Hunterand
Journey Into DarknessJohn Douglas page at AmazonI mentioned those to my wife and it just so happens she has
Mindhunter, so I just started reading it. Thanks for the tip. She also found another one of his buried somewhere,
Obsession.