He suffered a breakdown of the victim-selection process. He probably thought it would be easy to rob an 81-year-old. Home Invasion Suspect Fatally Shot By Elderly Homeowner « CBS Pittsburgh
So the 81-year-old woke up to find someone standing over him, demanding money.
The homeowner picked up a .22 caliber gun, which he had nearby and fired one round. It hit [the miscreant] in the abdomen.
While I wouldn’t count on a .22 caliber gun, one shot killed this guy. (His body was found nearby.)
No charges are expected against the homeowner, because self-defense is a human-right.