Photos that bug me

This is from National Geographic's "The Lost JFK Tapes: The Assassination," from about 26:55 into the program a DPD car drives in front of the TSBD and is heading into the Elm St extension which will take it into the parking lot area behind the grassy knoll.  What bugs me is the shirt on the hanger in the rear on the driver's side.

Now I know that the DPD either owned or had some understanding with whoever did own the land and they did park their cars there.  The County jail and the County Sheriff are right there on Houston St.  What I don't know is was it a habit of Dallas Police Officers to have their clothing on hangers on that little hook? Did they use that for their street clothes, or their uniforms? It bothers me because Tippit's police car also has clothing on a hanger on that little hook.  Now with the idea that people, perhaps assassins, could have dressed as Dallas Police Officers it just bothers me to see spare clothes in Dallas Police cars.

As you can see it does not appear to be the shirt of a DPD officer's uniform, and yet it seems to be nicely pressed, also the lock on the door is open. You can see the little knob is up against the backdrop of the shirt. Baffling.