Guys, even just a tiny .410 shotgun loaded with birdshot is deadly at close range.
Here is an autopsy photo from the FBI's website showing a man who was shot in the head with just a .410 using birdshot:
I would venture to say that this fellow died very quickly.
Now if you want to see a bunch of EXTREMELY graphic photos of what 12 gauge loads to the human body, buy a copy of this book:
Shotguns are extremely destructive at close range, no matter what size shot is in the shell.
P.S. - This news story at the start of this thread does not mention what gauge of shotgun this fellowed stuffed down his pants. I don't think that one can assume that it was a 12 gauge. A smaller gauge sawed-off shotgun would be easier to conceal.