I'm thinking alone the same line as yourself.I wonder if the dismemberment serves the purpose of ease of transportation too: moving between point A and point B with body parts in separate bags is probably less obvious and easier than moving around a whole body.
All MOO.
Was either done because they couldn't move his body as a whole or as to not draw attention when removing a body.
Other scenarios, dismemberment took longer than expected and they ran out of time or they encountered car trouble.
All moo