"Wife Swap" double murder suspect Jacob Stockdale used a shotgun to kill his mother and brother, both of whom were shot in the head ... according to cops.
Law enforcement sources tell us Jacob fired twice at his mom, Kathryn with the 20-gauge shotgun and left her body in an upstairs bathroom in their Ohio home.
Jacob allegedly shot his younger brother, James, once in the head near the front door ... then unloaded on himself about 10 feet from James' body. Jacob shot himself in the face with the shotgun ... and miraculously survived.
Sources close to the case tell us Jacob was trying to communicate with officers when they arrived, but they couldn't understand him. He was last listed in critical condition after being choppered to a hospital.
One last thing ... we're told Jacob's father was not home at the time of the shooting, and was stopped less than a mile from the home on his way back from work when cops broke the news.