Wow... Maybe it's a regional thing here in the South. The half dozen or so police/sheriff offices I have worked with don't want anything that even resembles a camera in the interview rooms.
For one project, we custom fabricated corner mounts for the Kalatel PIR covert analog cameras and they could see the entire room. The Verifact A mic worked great, put required a little testing and tweaking, the PD wanted it to pick up the slightest whisper or mumble, ceiling mounted it sort of resembles a smoke detector.
When they mean "anything you say can be used against you", they mean anything. An officer doesn't even have to be in the room. Many times the interviewee would start talking to themselves or break down crying once the detective left the room. Yup, they can use that.
Not sure if beads of sweat are admissable...