to the original post and folllow ons re: GZ, gun, concealment, residue, recoil
gun and carry :
That model gun is very small, intended to be pocket-able... so he could have had it concealed in waistband, pocket, inside waistband holster, etc... but it is most likely it was in a pocket because he no doubt bought the gun for it's compactness and ability to easily conceal, giving up other desirable features like larger magazine capacity and accuracy...
CCW issues, did GZ have the gun drawn?:
very unlikely, there is a mandatory 36 month incarceration for 'display' in Florida that all CCW classes drill repeatedly into students.... believe me, he knew he was looking at 3 years in prison if he drew it without very very good reason. That doesn't eliminate the possibility that he was simply crazy, but calling 911, knowing LEOs were a couple of minutes away, and displaying would have simply been insane...
firing of the gun:
I agree with the previous poster and would think that anyone with any sort of training in that scenario with a 6'+ football player mounted on him beating him would have struggled to get the gun out, then would have fired as soon as he got anywhere near a body hit, where he was relatively sure the round wouldn't have 'gone to background' meaning missed TM and possibly hurt someone else...
recoil, could it have caused injury to GZ?:
with a very deep level of experience, I would describe the possibility as very near impossible.... modern semi automatic handguns of that type have very limited recoil... especially in that caliber... 9mm luger is a small charge, very easy to fire and control round... to break his nose, the rear of the gun would have had to be very nearly physically in contact with his nose... a shooter holding the gun completely limply from 6 inches away from his nose and firing it probably would only see 1-2 inches of recoil, probably less... they were evidently struggling with the gun, so in my mind it would be much more likely that TM smacked him in the face with it, even on the incredibly small chance that it caused the injury in the first place...
at the very beginning of this video you see live firing of the Kel Tec PF9: note the amount of recoil... practically zero backward... about 1 inch muzzle rise.... just about anyone firing it would experience the same recoil because fo the grip / trigger force required to fire...
[ame="http://www.youtube.com/watch?v=wdd44jfgrLo"]PF9 Kel-Tec - YouTube[/ame]
various released evidence on ballistics and mortality:
while not an ME, I would note that the ME described the range as intermediate while the clothing reports said stippling etc indicating a contact shot... that all makes sense as the round penetrated at least the hoodie and shirt prior to entrance lowering the round energy dramatically and isolating the body from close range gunshot effects from gunpowder etc. so I don't see any inconsistency in the ME report vs. GZ and witnesses reports of a contact shot while TM was on top of him....
residue:
they both had jackets on, were struggling, etc. so there are a lot of variables... but in general, exposed skin on both of their faces, hands, and their clothing should have had significant amounts of GSR regardless of proximity... but I will add that a shot near either of their faces, meaning within about 4-5 inches, would have likely embedded powder particles in their skin, would have shown up on the ME and police reports, so I very much doubt an 'up high' type of shot occurred.....