A note for the uninformed. The Buk warhead is a bundle of hardened steel rods according a reliable source. The warhead is proximity fused and fires some distance from the target. It produces a shotgun like dispersion of rods which do the damage since the missile is travelling at Mach 3+.
There is thus no burning wreckage or blast effects. The image on page 21 shows perforations which look consistent with that type of warhead. Rods fragments should be found in the wreckage or the bodies. A high speed upset following loss of control might account for the airframe breakup.
Interestingly, bobik_57 is claiming that those marks provide evidence in support of an air-to-air missile:
bobik_57 - ??? ? ?????? ???????? ??. ?????? ?? "???-?1" (Google Translate does a passable job on the text).