Again, checking Geocaching.com would have answered all of this. If there was a "device", it would have killed the X amount of people who have found it so far already. No one is going to put a bomb in the woods, thats retarded.
If the cops still don't know what Geocaching is, then they have a serious education problem, considering that millions of people and families play this all around the world, and its been going on for almost 12 years now if I remember correctly. Go to the site, punch in your location. I bet there are a few within a few miles of where you're at right now. I'm not bashing, just trying to keep tax dollars from being wasted.