As the 20th century dwindled down, law enforcement forged into new territory to crime fighting by creating a "profile". Various psychologically trained, experienced investigators in the FBI and other law agencies began applying new ways of thinking in trying to identify and out think predatory killers, termed in the 1970's as "serial killers."
As a result some truisms emerged. These stereotypical statements were taken as gospel: most serial killers are white, of a certain age, certain socio-economic level and will prey on one gender or another, and always within their own racial or social comfort zones.
Thus, for the past forty years the strong belief that there were no women serial killers or ethnic serial killers. If found, they must be an anomaly. Yet, statistics about the personalities that can evolve into these types of killers indicate there are a lot of them in society. Thus, few possibilities of anomalies but rather a pattern undetected or under recognized.
Then, however, was Jake Bird arrested in 1947 for killing two women in Tacoma, Washington. Various newspaper accounts of the time reflect an intelligent, even savvy, man in his 40's. He implied and claimed connection to over 40 murders in a half-dozen states. He favored using an axe but a knife worked as well. His favorite target were white women usually in their 30's to 50's.
So - - one major prop is shuttled aside in this one case. Rather than being an exception that proves the rule, it may be the exception that indicates the basic rule is flawed and too restrictive. One of the guiding principles for early serial killers was a limited field of operation. Society was not as mobile and options were limited for them to act out their dark desires to kill. As a result there would tend to be a similarity in selections of victims; the killer would tend to be in places where he felt invisible, safe or easily accepted without questions. As society became more mobile, there tended to be a shift in the selection of victims and they were not as cookie cutter as mystery novels might imply. Issues of opportunity were enlarged with the ability to get away swiftly. Most importantly, a killer who did not feel he fit into society anyway, who had developed skills to help him, or her, retain a low profile and move with ease through various realms of society, began to prey on a wider variety of victims.
So many states have long, long lists of missing persons or unidentified bodies going back decades. In researching some of these, it is often clear that working under assumptions of motivation, victim selection and methodology, police were often hampered in connecting victims to a predator.
Is it time to go back to the criminal investigation drawing board and start fresh with an assumption, "everything you know is wrong?"