An actual case a few years ago in Montgomery County, A suburban area near Philadelphia, PA.
Guy wakes up hearing banging on the outside door. Arms himself, and opens door. Naked man enters residence. Homeowner backs up yelling. Opens fire. Wounded intruder exits house, homeowner follows out into back yard and follows through with 2 to the head as intruder is collapsed on the ground. Later discovered, intruder is drunk, he habitually walked into the backyard of the condos to urinate at night. He is the neighbors son, (36 or so If I remember correctly) he was not known by the homeowner. Trial underway, homeowner has had heart attack, is in poor health, was Veitnam vet, and clames he was taught 2 to the head in training. Trial result. Guilty - bad shoot. It was the following outside and the 2 to the head that made the decision to charge. If I remember he got 20 or so years. I don't know what that will actually be.
Lessons learned: use your gun efficiently. This man used a 9mm in an inaccurate manner.
don't follow outside your residence. See above and make sure you don't need to.
The intruder was also shot in the back as he was leaving the residence, but that was not the stated reason for charging him. The two bullets were removed from the ground under the intruder's head for use at trial. This was a bad thing for the shooter.
Lumper