not to be too graphic, but generally a shotgun IME does a lot more damage to flesh bone and cartilage than certain other weapons. Also a big variable is the proximity of shooter to victim.
http://library.med.utah.edu/WebPath/TUTORIAL/GUNS/GUNINJ.html
http://www.pathologyoutlines.com/topic/forensicsgunshotwounds.html
http://www.exploreforensics.co.uk/entrance-and-exit-wounds.html
http://www.relentlessdefense.com/forensics/gunshot-wounds/
A little light reading on entry and exit wounds and how different they can be depending on weapon, proximity, etc.
I can imagine in a catastrophic injury such as a head shot, it is my opinion there would be a lot of blood, which would make initial persons on the scene unsure if they were viewing an exit or entry wound.
I'm definitely not an expert at interpreting autopsy reports, but I'm not seeing anything about an exit wound in the written part, and there's no exit wound diagrammed anywhere that I saw. jmo