Criminal profiling is "the act of drawing on prior research and knowledge to create a psychological profile of an unknown criminal offender." How does one go about profiling a case? A detective or special agent looks at these four aspects to gain insight on the personality of the suspect: antecedent (what caused the suspect to act when they did?), method and manner (what type of victims were chosen, and in what manner were they treated?), body disposal (did the crime and disposal take place in one scene, or multiple scenes?), and post-offense behavior (does the suspect try to put himself into the investigation?). It is thought that a suspect will unconsciously leave clues due to their very own psychology. Because of this, profilers tend to also look for which gender would be more likely to commit the crime, any fantasy that seems to be involved, a ritual the perpetrator may have used, a signature left at the scene, and whether a "trophy" (something from the victim) was taken. The answers to all of this can provide details to the suspects inner thoughts which gives those investigating the case a better chance at catching the offender.
But how reliable is it? Since it's start in 1940 by Dr. James A. Brussel, criminal profiling has been subject to scrutiny. A study done in 2002 by Kocsis, Hayes, & Irwin, showed that chemistry majors produced more accurate profiles of a murder than experienced detectives and officers did. Many myths surround profiling as well. Popularized by Sir Arthur Conan Doyle's character Sherlock Holmes, it is thought that criminal profilers are born, and cannot be taught. This is not true, and the book "Criminal Profiling" by Brent Turvey points out that criminal profiling is a systematic process that can and should be taught to law enforcement officials.
Popular TV series, like Criminal Minds, show criminal profilers at work. In this clip we see Agent Emily Prentiss show another unit's detective what profiling is all about.
Despite its flaws, criminal profiling is a process that the FBI and other law enforcement organizations continue, and will continue, to use.