Why would anyone waste an expensive asset like a MANPAD on a low value target like a Papa Charlie full of nobodies?
Supposition by unqualified people will merely lead to confusion. Just looking at pictures will not tell you if explosive residue is present which is about the only really conclusive way of determining if an IED or a MANPAD was used. Did your investigator have wreckage analysed by a reputable lab for these traces?
Try Occam's Razor on this one.