Many organizations-from courts to prisons, and even the FBI-hire Forensic Psychologists. In court, you work with Lawyers from both defense and prosecution, determining whether a criminal is sane enough to stand trial, selecting jury members based on psychological profiling, evaluating witnesses, or giving expert testimony. You can also provide PTSD therapy for victims, help make decisions in child custody hearings, or evaluate the psychological damage done during a crime.
In prison, you primarily act as a Therapist. You might run group meetings, work one on one with repeat offenders, or serve on parole boards by predicting the possibility of a criminal's relapse. You also use your knowledge of therapy techniques and human psychology to help imprisoned people resume normal life after their sentence.
For the FBI, your work is mainly to create psychological profiles of criminals. When faced with hard-to-solve crimes, you use previous research and knowledge in the field to narrow down the search to a certain personality type or person.
A lot of your knowledge comes from hours of interviews with prisoners. You work to figure out why a person commits their crimes, and how they do it. This information helps in future cases with copycat crimes.