- Does anything connect this vehicle to the accident?
- Did it look damaged; as though it had been in a crash?
- Did it look like it was fleeing or driving erratically?
- Was there anything suspicious about the vehicle or the driver?
Police would have deemed the photo irrelevant and moved on. But that didn't happen in this case.
Their failure to do so doesn't have to do with source of the image (Flock, shop CCTV, dashcam), but with their inexplicable lack of rigour.