Yes, but if they were taking that action, they would have instructed the public land officials on a cover story, not allowing them to create a mystery out of and open those boxes.
Imagining movie style capers like this is emotionally engaging but pretty distant from the reality of these situations. Assuming you can put lightning into a bottle is extremely dangerous. Most police work involves a lot of methodical boring stuff, not a brilliant technical deception.
So the "hack into them" part isn't quite right. But they certainly do intercept and analyze various signals. Which is generally the boring and tedious part. But right or wrong, it is sort of the standard play for the feds to let some criminal activity continue to gather additonal intel.
