Forensic Psychologists can play a number of key roles in a criminal investigation. Immediately following a crime a forensic psychologist may be asked to act as a criminal profiler. It has over the years become the love child of numerous television programs, movies, and crime novels. Criminal profiling involves the psychologist using his understanding of human behavior, motivation, and pathology so that he/she can create a psychological profile of the offender. The profiles can be surprisingly accurate. From observations of the crime scene one can infer the behavioral characteristics of the individual who created it. To a profiler everyone is a slave to his or her psychological makeup. In turn, profilers use their knowledge of which the typical offender is that bears these characteristics and then predicts not only how the investigators can expect the offender to behave in the future, but also what their physical appearance will likely be. While profiling may seem very exciting, few psychologists are ever involved in this field. Psychological knowledge has been applied to many more areas of investigative police work, from the police interrogation to the police line-up. Both of these areas have prospered greatly from psychological research.
Outside of the "front-end" operations of police work there is numerous opportunities for the application of forensic psychology. In the court system, Forensic Psychologists are frequently used for both criminal and civil cases. In the criminal realm, the forensic psychologist is often asked to assess competency. Competency assessments can serve a number of purposes. First, a defendant can be assessed for the ability to stand trial and/or make legal decisions on their own behalf. These types of decision have been frequent in the news. These evaluations are carried out when the defendant appears to suffer from a mental defect, such as an acute psychiatric disorder (i.e., scizophrenia) or a mental disability (i.e., mental retardation). Secondly, Psychologists may also be asked to make an evaluation regarding the defendant's mental state at the time of the offense. The entire "not guilty by reason of insanity" defense relies on the psychological evaluation of a defendant's inability to form criminal intent.
Frequently, people forget about the applications of forensic psychology to civil law. Often a forensic psychologist is asked to make evaluations of defendants or plaintiff’s disability or level of trauma. From these evaluations the court can decide whether compensatory damages should be provided. Civil-Forensic Psychologists also work on child custody, sexual harassment, and immigration cases. Virtually any civil matter that requires psychological evaluation may include the work of a Forensic Psychologist. It is important to remember that not all Forensic Psychologists work with violent criminals.
The Forensic Psychologist that investigates the social-legal components of the common law court system can provide influential knowledge to both criminal and common law cases. Forensic Psychologists often are asked to evaluate potential jury members. To this date numerous ‘mock'-jury investigations have been published. These Psychologists identify jurors who are potentially prejudicial to their case, and whom can thereby be eliminated from the jury panel during jury selection. Many social-legal psychologists are also experts at how to psychologically motivate witnesses. They will inform the lawyer of potential questions that could stump a witness or set him/her off on a tantrum. Such theatrics can be very influential in a trial.

Most Forensic Psychologists work either in a correctional institution or in a psychiatric hospital. In this environment they will perform a number of important roles. One of the most essential roles is therapeutic intervention. The Forensic Psychologists pay an important role