Regarding the pic of the fire pit, it looks like a lot of dirt was disturbed around the outside of the cinderblocks. Maybe he had to do a lot of digging, maybe getting rid of some dirt with evidence on it. It seems like an unusually wide area to dig if you just wanted a fire pit. And the shape of the digging is unusual.
some of the areas would be dirt thrown out of the hole (there will be leftover dirt because the hold is “occupied”), and other areas where he may have encountered rocks, hard clay, etc.