1) Large and/or aggressive breed of dog? YES! Owner thought an appropriate method of control was a stun gun.
2) Running loose, often >1 running loose? YES! Two pits packed up to seek and destroy.
3) Previous reports of aggressive behavior? Not reported.
4) Unrealistic expectation of gentleness from owner, often despite #3 above? Yes and no. Yes in that he thought nothing of opening the door and letting them out while he stayed in, no in that he figured the only way to control them was with a stun gun.
S0me years ago a pit bull was mauling a child in one of the Atlanta neighborhoods (big surprise there) and the owner was just watching. A neighbor ran in his house and got a .357 and shot the dog. At that point the owner attacked the neighbor screaming “Don’t hurt my dog. Don’t hurt my dog.” He shot her too. She survived actually not badly wounded. The dog didn’t. The owner was convicted and actually spent some jail time for attacking the guy with the gun. (all in an Amish neighborHOOD)