I'd be surprised if there were a mix of hidden and open cameras, because at that point, why have the open ones? Though who knows.

That said... I'd suggest treating this like a trump card in that if you use it, you'll probably get yourself and anyone who's covering for you in trouble, but if you need that last bit of evidence, well, you do have this camera. Otherwise maybe some kind of elaborate cover story? I mean, you're all creative folks.