Maybe they should take a closer look at the coffee shop or newspaper stand nearest the defense establishment or cafeteria within it. I would think that if you're using coins you would arrange to be the last place a target shops befoe entering such a facility so that your coin would do its work before he goes elsewhere to spend money. Pick a microbiologist and pass him the change, etc, find out where the lab is. I suppose with these you could try to locate a specific lab within a defense complex or trigger some other device or at minumum alert someone who's busy snooping in offices within that an individual so tagged is about to return to his office and it might be wise to leave. Weird.
Agreed.