Offender profiling is a criminal investigative tool that allows inferences to be made about the characteristics of a likely offender based on the behavior exhibited at a crime scene or a series of crime scenes. It draws no definitive conclusions about the individual, but rather depends on probabilities to create composite picture of the likely traits of the individual who committed the crime. It functions as any other piece of forensic evidence in an investigation, operating to narrow the search parameters of law enforcement authorities. Because the technique has been used in many sensationalized crimes, the public has developed an inflated regard for the value of offender profiles in investigations. Law enforcement authorities, however, recognize that it is an important but limited tool that is used in conjunction with other forensic evidence to help discover the identity of a perpetrator.
Offender profiling was developed as a response to violent crimes, usually with a sexual component, perpetrated on strangers. Such crimes are usually accompanied by a high degree of publicity, which increases anxiety in the community at large and places a great deal of public pressure on police to solve the crime as soon as possible. These types of crimes are extremely difficult to solve, however, since there is no apparent connection between the perpetrator and the victim, and are often referred to as “stranger crimes”. The selection of victims is often random and based on criteria and a logic pattern that makes sense only to the offender. As a result, the forensic evidence from the crime scene is generally inadequate to narrow the search sufficiently to identify the criminal. This forces law enforcement authorities to spend a considerable amount of time investigating a broad range of suspects. Most police forces and particularly those in smaller communities generally do not have sufficient resources or expertise to cope with an investigation of such wide magnitude. The offender profile helps to focus the efforts of police by narrowing the search parameters to a defined set of suspects who exhibit a certain set of behavioral or personality characteristics. It acts as a means to draw the attention of police to an investigative pattern consistent with the forensic and physical evidence.
Basically, the offender profile examines what took place at the crime scene, determines the type of person that committed the crime, and generates a profile of likely characteristics and behaviors of that person. In large measure, the profile is based on a body of data obtained by examining evidence and methods of operationemployed by criminals in previous crimes, as well as psychological and sociological studies. It matches the evidence from the present crime against those used by other criminals and crates a personality profile based on the correlation of probabilities. Therefore it is the product of a series of assumptions regarding the similarities between past and present crime and is not absolutely accurate.