S1·E16 Gemini

When Leo sees disturbing similarities between the science fiction movie for which Rollie is providing the special effects, he begins to suspect the movie's director is a serial killer who terrorized Central Park four years ago and was never caught. He talks Rollie into using FX to get him to confess, but they soon discover the director has a dual personality and his murderous ""other"" is now taking over, ready to kill again.