I can’t imagine anyone using a real wire today. A wireless transmitter is about the size of a penny. You see occasional video on those “real cop” type tv shows where the footage was shot from some guy’s baseball cap cam or some gal’s purse cam. If the guy takes off his hat and sets it on the table and it still manages to record the entire proceedings, you can be darn sure the guy didn’t have a wire running down to his undershorts.
I think it’s more likely that you’d have a bunch of FBI guys later pouring over a table of pocket change going “which one of these quarters is our bug?”
Of course, old habits die hard. I can picture some mob thug patting down some guy looking for a wire, not realizing that the guy’s shirt button is broadcasting everything he says out to a van half a mile down the street.
I don’t know what the FBI actually uses, but they certainly have better stuff available than old fashioned wires. Heck, here’s a web site that will sell you sunglasses that have a hidden camera built into them:
If you and I can buy this stuff, imagine what the FBI has?