Did the second autopsy actually state that a hole "had been drilled into the hyoid bone" (I suspect that there would be evidence of tool markings/drilling of that hole)? If so,
please link to the report.
Or simply that there "was a hole in the hyoid bone"?
Can this be naturally occuring when such a small bone is left in the harsh elements for such a prolonged period of time? I ask this because it's actually a 'thing' in these parts to search for rocks with holes worn into them by the elements and salt water. Those are rocks. Seems to me, that same natural erosion could also easily occur to a small human hyoid bone that is also laying exposed in same enviornmental circumstances in a much quicker timeframe.
Hag Stones / Adder Stones