” only someone who had placed it there before would have known the location of.”
Right. This kid was not local. How did he know there was a ladder there? Did he scope the site out in advance? Or did he have help? I don’t have a beef with the sniper, unless he saw the shooter before he fired and did nothing.
Even then, the ground crew should have removed it, used it to put someone on the roof, or watched it from a hiding spot to see who used it.