Yeah, but who did it? All five of them, one of them, another cop not at the scene but with access to the system? Contractors with system access? It's not enough to be sure that a crime happened. Which isn't to say there shouldn't be an investigation or measures taken to make it harder to happen.
And to be more careful, what's the failure rate on those cameras and how many incidents happen a year where it would look suspicious if all cameras fail? If the numbers are high enough we might just have selection bias.