NOT HIDDEN!!
Very visible
A family member had a store- she had a shoplifting problem- she was going to put in hidden cameras- I asked her if she wanted to catch them stealing (and spend time prosecuting) or prevent stealing?
She put very visible cameras in, and shoplifting went way down.
I am not against hidden cameras TOO.
That is an even better idea! BOTH. That way, if the footage is manipulated on the visible camera, the hidden one will show the deception. Brilliant!