The people claiming that you're making "strawman arguments" about the role of the DPD are the same ones saying the revolver was planted, Oswald was railroaded, he was denied due process rights, witnesses were coerced into implicating him, police lineups were staged et cetera. But damned you Mr. Strawman, you're just making things up when you say they say the DPD was involved.
Our contrarian CTers are like Inspector Clouseau. They suspect everyone, and they suspect no one. All the evidence is potentially the product of fakery but they are not suggesting anyone faked the evidence. If they did fake the evidence, that doesn't mean they were involved in the conspiracy to kill JFK and Tippit etc. Round and round they go down the rabbit hole. There are so many logical inconsistencies that you have to wonder if they really believe their own nonsense or if they are "just here for argument" like in the Monty Python skit.
Here we learn that for some unspecified reason that the DPD might have planted the gun on Oswald to frame him for the Tippit murder but these police officers might not be in on the larger conspiracy to kill Tippit. There are multiple parallel conspiracies going on. It is just a miraculous coincidence that all these conspirators are working for a common purpose. Imagine the luck of the JFK/Tippit conspirators behind these crimes that the DPD decided to plant a gun on Oswald to frame him for the Tippit crime. Which is exactly what they wanted to happen! What is the contrarian evidence that the DPD framed Oswald by planting this gun? Because in the history of law enforcement there have been SOME instances in which the police framed a suspect. That is it. The DPD decided on the fly to frame some guy at the TT for the murder of a fellow police officer. Quick as a bunny they found a spare gun that could not be traced to anyone to plant on him. Not caring that perhaps the real murderer would go free or worse for them be arrested bringing into question the "discovery" of the murder weapon on Oswald. They just had it in for Oswald - who they didn't know from anyone. Why not plant the gun on the guy at the library? A contrarian mystery. What is the proof for all this? None. It is just "possible" or at least not "impossible" to disprove the possibility to their subjective satisfaction. Lunacy.
