Criminal psychology is the study of the thoughts, intentions, and reactions of criminals in order to understand criminal behavior. Criminal psychologists are often called as expert witnesses in court cases to help the jury understand the mind of the criminal. Criminal profiling involves analyzing evidence from crime scenes to develop profiles of likely suspects based on behavioral characteristics. Profiling aims to narrow the pool of suspects and help police investigations. Forensic psychiatrists may also evaluate defendants' mental states at the time of a crime to determine criminal responsibility.