For the record, I am completely unfamiliar with the geocaching angle or hobby. The first time ever I checked that symbol was in another case in Texas (MB) due to the similarity of a monument sign with that symbol(..). When I processed the image of the POI again a couple of days ago, I used another algorithm and saw immediately, what it could be.
Now, I am saying this is this or that. I don't even claim, there is a logo for sure. I am just saying, I processed it very lightly (!) and this is what came out. Some programs have great dynamic ranges and previews and let you fine tune to a t.
Same goes with the shirt design. I have no clue, what it is, could be something completely different. I can only go, with what I see.
I don't know, if the victims were geocaching. I don't know, if the BG was geocaching. What I do know is, that it would be a great "excuse" to be just anywhere in the landscape IMO.
Thanks, Nin