So how did the black sweatshirts wind up on the parking lot outside the vehicle??? and why were all four doors opened???
How did the shooter’s car find its way to the parking lot? Did anyone see it get there? Didn’t think so. Worthy of more study.
“So how did the black sweatshirts wind up on the parking lot outside the vehicle??? and why were all four doors opened???”
There are other possible answers than to believe the police enforcement contaminated the scene - which is what your narrative requires.