The first thing they will need to do is figure out the context of the human remains. Are they archaeological? Are they historic (e.g., from an old unmarked cemetery)? Or are they modern, and thus potentially of forensic/prosecutorial significance? Additionally, I have no insight into the specific details of the human remains recovered, but the term "bone fragments" does not imply purposeful dismemberment or disarticulation. Bones naturally decompose and fragment over time, especially in the outdoors where they are subject to a host of taphonomic forces (e.g., sunlight, moisture, scavengers, etc). So I wouldn't necessarily read anything into that unless the fragments retain signatures of sharp force trauma (cut marks, saw marks, etc.) denoting purposeful action.