It will take lots of time and people to truly mess with the forensics.
For every bullet they need to find a firearm at the scene.
So, turning 223 holes into .38 holes would take a major conspiracy. I think too many felonies involved for it to happen that way.
We are close to knowing (reports) that 4 officers fired multiple rounds from distance. I think they evidence is not looking good for the on-scene LEOs.
I hope you are right. So far it looks as though the cops, judge, prosecutors and public defenders are in cahoots. Not too long ago there was a prosecuted finally caught withholding evidence for years, some of them death penalty cases. Also reports of shifty forensic labs.