This tv series goes through the explanation of how behavioral science became in existence within the FBI due to interviews with serial and psychopathic killers still in prison to this day. The series takes place in the 1970s when people were not advantaged by technology. This show was extremely well presented, contained excellent gritty interviews that will make the viewer want to watch episode after episode. It is not quite necessarily a documentary, as it is the beginning of an understanding of how serial killers are formed.
https://www.youtube.com/watch?v=7gZCfRD_zWE
