I've never seen the movie Gothika, but I did a quick search for information about it on the net. From the brief things I saw, it sounds like she worked on an inpatient psychiatric unit for criminals, or suspecticed criminals. It sounds like she was being portrayed as some type of "forensic psychiatrist". In order to become a forensic psychiatrist, you'd probably be best off to do a forensics fellowship after you finish your 4 year psychiatry residency. I'm not that familiar with forensics fellowships, as we didn't have one at University of Iowa where I trained. I believe they are generally 1 year fellowships.

I believe the main organization is The American Academy of Psychiatry and the Law. You can check out their website for information. Unfortunately, the link for students seems broken - but I'm guessing that page would have the information you are looking for.