I'm not disputing it; I think it was the aunt. So far, I have read no statement from the parents except the father's offer of condolences to the families of the slain, which was decent of him, after having produced this monster. But it wasn't the parents of the shooter, initially, who dogged the gun lobby.
I was afraid this crime would be instantly politicized by the gun people, even though the majority of these killings were by knife and ramming with a car.