A committee of the Texas legislature has put out a report:
There were earlier reports that a policeman could have shot the killer; this report says that person was not the killer but instead “The officers testified to the Committee that it turned out that the person they had seen dressed in black was not the attacker, but instead it was Robb Elementary Coach Abraham Gonzales. Coach Gonzales had been on his way to the parking lot to leave the school after his lunch duty when he heard a gunshot and then Coach Garcia’s report about the attacker over the radio.”