I honestly don't know. I got this one off of FOX TV news (a source I usually trust) but I don't watch the news too often.
Anyone with a little training and a scoped rifle could replicate this disgusting crime. Silence is not really a factor as all of the crimes have occurred very close to freeway on-ramps, providing quick escape.
I hope the S.O.B.s involved are struck dead, and right soon.
It is the only one that any witnesses have reported hearing. I've been wondering why no one at the school has said anything about hearing a gun shot. Lots of stuff being kept close to the vest on this case. The 223 is a "small game" load. Max. distance of about 400 yds. but, not very accurate at that distance. At 100 to 150 yds. acuracy is is fairly good.
There have been many more witnesses that heard a shot. In addition to those noted here by others, Fox also interviewed a truckdriver who was across the road from yesterday's shooting. The guy is also a hunter, and he was absolutely certain that what he heard was a rifle shot -- before he saw the victim.