PTSD is diagnosed by symptoms. As you read through this page, keep in mind that it takes a professional who knows PTSD to diagnose this disorder from other disorders. One supervisor recently asked me how anyone can separate those with PTSD from the variety of other mental disorders, or those faking it. My answer to this question: the same way you recognize a Volkswagen. There is no substitute for a trained experienced psychologist/psychiatrist that works specifically with PTSD, and especially one that knows the social environment in law enforcement. Part of the problem with this disorder is that there are far too few that have a lot of first hand experience with PTSD and cops.