I suspect that they also spent a lot of time reviewing the exact phrases used to answer questions about recording.
I read some interesting specs for a PD dash cam. It included "retroactive" recording - which simply meant that it is always recording to a circular buffer when turned on, and there is a certain non-trivial amount of time during which a "retroactive record" (ie, "do not discard" command may be entered to prevent recently captured info from being dumped). Also, with modern disk technology, the amount of video that may be saved to a $100 hard drive is impressive, and the amount of audio that will fit on such a drive is staggering.
It certainly would not be hard, or even that expensive, to build a system that saves/records all audio within earshot - the only thing we have to go on in this case is SpotShotter's and the government's word.... I think equipment like this should be open source or subject to freedom of information requests.