They've released some info, now that they decided not to charge him:

The burglars had stolen from the garage earlier in the day, and came back to burgle the house.

Zach, 23, a qualified small airplane pilot, rushed down stairs with his AR-15 assault rifle.

As he turned a corner from the hallway and into the kitchen he saw the masked intruders and sprayed them with gunfire.

His bullets thudded into the walls and refrigerator and also killed the three youths with each suffering a single bullet wound to the upper torso.

Zach, in his 911 call told police he had shot two burglars and did not realize that a third had crawled out of the house and had succumbed there.