I would be very interested to hear if it is ever determined exactly how the weapon got loaded. As has been mentioned the violation of rule #1 resulted in this bit of negligence, which brings me to a subject near and dear to my heart. It is unimportant if an "antigunner" tried to plant a round, it should have been caught by a "progunner" long before.
In the course of my twenty four years as an Infantryman, Bradley Master Gunner (which simply means I spent a lot of time training units on using and how to use live fire ranges), senior NCO and responsible gun owner, I observed some shocking instances of firearms safety violations, some resulting in deaths. When I was in Iraq, one of the most dangerous places were the clearing barrels placed at the entrance way to forward operating bases. Often, many units would be there clearing weapons, with the theater wide policy being mandatory of doing so (due to the fact that negligent discharges were frequent inside the FOBs in past experiences). I witnessed numerous events which would startle most veteran gun owners, whether they served in the military or in LE or not. Many individuals simply don't understand how semi- and fully automatic weapons work (in the military, they can be very different), even trained personnel (which, on some level, they all should be)! However, the clearing barrels helped save lives by requiring the idiot to place the barrel of the weapon into a barrel filled with sand. The Army rarely referred to an incident as accidental ,but referred to them as negligent and my unit (1st Infantry Division) required some form of Uniform Code of Military Justice punishment be meted out to offenders. I could cite stories that would shock you of the violations that I witnessed both in combat zones, peace-keeping missions and on ranges at homestations/garrisons, by all ranks, duty descriptions, etc.
It's really easy, never assume a firearm is unloaded, even in your own house. Recently, I took a hunting course here in Germany where I live and work (for the US Army, but I'm retired Army now). The instructor, who was an American, brought a scoped rifle in to demonstrate how to measure the eye relief distance for an individual. I watched him clear the rifle, then he had each of us come up and check the eye relief. Not one of us, including myself, cleared his rifle, and yet I knew I should have, I didn't want him to think I was being cheeky by double checking him. He didn't say a word until everyone was through, and then he told us that the normal German run course instructors would have failed us for not clearing the rifle (he gave us all a break). It was an excellent teaching point. Unless you yourself clear a weapon, you must assume it is loaded, plain and simple.
