I think that they are lying.
OK, but realize how big your conspiracy just got.
You've got to corral the management and worker bees at both the ATF (ballistics) and FBI (video analysis), and probably the docs/medical personnel doing the autopsy work at the Southwest Institute of Forensic Sciences.
If this was really a planned op don't you think they would have tried to contain the number of people that had to be in on it?