Prior to the conception of "The Thin Blue Line", Morris originally planned to film a documentary about prosecution psychiatrist Dr. James Grigson, known as Doctor Death, who testified in more than 100 trials that resulted in death sentences. As an expert psychiatrist, Dr. Grigson made a name for himself by giving testimony in capital cases for the prosecution. Under the law in Texas, the death penalty can only be issued if the jury is convinced that the defendant is not just guilty, but will commit violent crimes in the future if not put to death. In almost every instance, Dr. Grigson would, after examining a defendant, testify that he had found the individual in question to be an incurable sociopath, who he was "one hundred percent certain" would kill again.