BOESP,
One of the results discovered at the Body Farm was that typically serious head fractures do not simply radiate out from the point of contact. Apparently once a fissure or radiating crack reaches another point of demarcation, say an eye socket, it will radiate backwards in a non-linear fashion creating another fissure, alike the cracked egg look.
So I think you are correct, but it would be more than an educated guess that could be offered.
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UKGuy, is what you are describing the comminuted region of the fracture? The radiating egg-shell portion is on JonBenet's skull but a linear fracture extends all the way from the occipital area (the mid-line region, or lower-middle back of the head) all the way to the front near the right eye socket (and a shorter linear fracture also runs to the back [posterior] from the comminuted fracture). That suggests, to me, one of two events. Either two fractures "met" each other or else it describes one event of a low-velocity+high-pressure type. This is, of course, just my opinion.
A striking blow of the 300-pound gorilla type should introduce massive damage to the brain tissue and covering under the skull. The autopsy does not state massive damage at the comminuted region. It describes what would come from a low-velocity impact. Note also that the scalp was not broken at that area of impact.
I know I'm jabbering about already cussed and discussed evidence but correctly analyzing that head wound and the ligature strangulation is so important to understanding what might have happened.