And how difficult would it have been for a professional to dress the scene with that stuff, make the shots, and leave the scene in the confusion?
If Oswald did happen to be a government informant, he would have been sent somewhere during that time period and then be just as surprised as he seemed to be, pointing at his black eye and complaining about how rough the cops had been with him - and looking forward to his goverment handlers coming forward straighten the situation out.
Looks like they did when Ruby showed up.
Precisely!