Criminal profiling is a frequently misunderstood phrase. Profiling refers to a process by which law enforcement officials, frequently criminal psychologists or criminologists, attempt to learn more about an unknown criminal by studying evidence left at crime scenes. By studying the behaviour of a criminal as well as their victims, the location of their crimes and other factors, law enforcement officials attempt to better describe the perpetrator for which they are looking. The only real cons of criminal profiling come when it is done poorly.
Assuming the police do not know who committed a crime and do not have a physical description of the criminal, crime scenes can give police evidence about the person who committed the crime. Crime scenes may give police information about where the individual may be located or where they are likely to commit future crimes. It can also give them physical information about the persons. Subtle evidence at the crime scene can give them information about such things as height, weight and physical strength.
This is one of the more subtle areas of investigation. By studying things, such as who the victims are, how their crimes are committed and how the criminal reacts to police or media attention, can give criminal psychologists information about the criminal. This could include information about motivation, psychological troubles, even clues about age or psychological age. Such information can help police determine where the criminal is likely to strike next, or who their next victim might be. Reviewing past criminal profiles or cases might even give them potential suspects or tell them exactly for whom they are looking.
Stereotyping is a bad idea in many situations. In the sense of criminal profiling, stereotyping means adding information to the profile that is not supported by the crime scene. Examples of stereotyping in criminal profiling might include assuming that a bank robber is poor or assuming that a rapist is single. Stereotyping runs a risk of focusing on the wrong suspects and excluding guilty people from suspicion.
Stereotyping received a great deal of attention after the attacks of 9/11. As has been concluded by the Justice Department and others, racial profiling is one of the worst forms of stereotyping. Not only does it run the risk of ignoring potential criminals but it doesn't narrow the list of possible suspects sufficiently. Assuming, for example, if there is an assumption that act of terrorism was committed by a Muslim, that only narrows the list to 3 million people and that only considers Muslims in the U.S. It also ignores the fact that the Oklahoma City bombing was committed by a non-Muslim.