I'm not a ballistics expert either,and FWIW,I lean towards the theory that the cartridge casing was probably dropped there by someone hoping to throw a monkey wrench into the gears. Having said that,however,a .22LR is certainly powerful enough to kill with. And the bullet wouldn't necessarily penetrate the body,especially if it's match ammo,which is loaded to low levels to start with,for the most part.(In fact,if the lighting is right,you can sometimes watch the bullet on it's way to the target.)