Criminal profiling is, in the simplest terms, the application of psychological profiling to the identification of criminals. It is often used by investigators who require a more directed analysis of evidence in cases where there are few or no leads, as well as by attorneys, both for prosecution and defense.
There are two main schools of criminal profiling, which have only recently arisen, as the discipline is quite new, and in recent years, as criminal profiling has become professionalized, the rift between the two has deepened.
Inductive profiling is the older method of the two, and it is currently used by the Federal Bureau of Investigation's Behavioral Sciences Unit, created by John Douglas, author of the books Mindhunter, Obsession, The Anatomy Of Motive, and the Crime Classification Manual and one of the bases for the character of Jack Crawford in the book and movie "Silence Of The Lambs" by Thomas Harris.
Inductive profiling is used to draw conclusions about a particular crime or criminal based on other crimes and criminals with similar elements.
Oftentimes, inductive profilers are experienced investigators given some limited training in psychology. Several famous inductive profilers are FBI special agents, such as John Douglas and Roy Hazelwood.
To aid the process of inductive profiling, the FBI aided in the development of the Violent Criminal Apprehension Program, or ViCAP, which is a national clearinghouse for information on violent crimes. In addition to aiding inductive profiling, it also helps reveal linked crimes.
Also, at least according to Douglas, inductive profiling can be used well in proactive techniques. In the book Mindhunter, Douglas describes these techniques in fair detail as they were used to catch Wayne Williams, who was convicted for a rash of child homicides in Atlanta in the early 1980s.
However, recently, inductive profiling has started to face a more hostile reception in the courts. Courts have dismissed the testimony of several FBI special agents acting as profilers, including Roy Hazelwood, on the grounds that inductive profiling is at best unscientific and at worst guesswork in a cheap suit.
In recent years, deductive criminal profiling, or behavioral evidence analysis, has come into more common use as the discipline of profiling has been more professionalized and inductive profiling has appeared to founder.
Perhaps the most visible behavioral evidence analyst is Brent Turvey of Knowledge Solutions (http://www.corpus-delicti.com). His book Criminal Profiling is currently the standard text on the subject.
Behavioral evidence analysis requires less investigative experience than inductive profiling, but more training in psychology.
Usually, where an inductive profiler will act as a consultant for a moderate duration in a case, the behavioral evidence analyst will simply provide either a criminal profile of the subject, if there is enough evidence, or a threshold assessment, which is used to suggest leads and provide investigators with a direction if there is not enough evidence present.
Behavioral evidence analysis differs from inductive profiling in that it attempts to assemble the evidence of the case in such a way that the behavior of the criminal can be reconstructed, and then to interpret the behavior as evidence that can be used to classify or individuate the criminal.
Perhaps the most difficult aspect of behavioral evidence analysis is that it requires a full forensic reconstruction before work can begin. This is, in part, due to the difference between the schools that inductive profilers never question evidence that they are given, but behavioral evidence analysis demands an equivocal analysis of all evidence.
Because of this, it is quite common for a criminal profile rendered by a behavioral evidence analyst to be somewhat incomplete, in that no conclusions are drawn without evidence. This is in contrast to inductive profiles, which are often derided as all sounding the same; male, between 20 and 40 years of age, self-esteem problems, overweight, and so forth.
The canoncial example of an equivocal analysis is given by a case in which a woman's body is found, and there is evidence of recent sexual intercourse. One might assume that rape was committed in addition to homicide. This is not the case. The woman merely had sex with her boyfriend prior to the murder.
The deductive profiler classifies specific behaviors, as opposed to the inductive profiler, who categorizes criminals. The categories used by Turvey are profit, opportunism, compensation, entitlement, anger, and sadism.
It is worth mentioning that Brent Turvey has never been successfully challenged in court. This has caused the FBI some degree of embarrassment.
References:
Mindhunter, John Douglas
Obsession, John Douglas
Criminal Profiling, Brent Turvey