We have a mach zhender type interferometer that can receive quantum bullets. Charlie fires the bullets continuously into the device and (assuming a perfect experiment) the bullets all exit at output A. Bob sits safely at output B. Alice is somewhere along the two paths that the bullets can take and chooses to block them, therefore, with 1/4 chance a bullet exits the interferometer at output B and, assuming it does, kills Bob. So, my question is...Who killed Bob?
Who made the last conscious choice to act, knowing the likely outcome of his/her action? Does Charlie reasonably believe that his bullets will continue to miss Bob because he doesn't know about Alice? Does he know that someone might possibly block the safe path without him seeing it, and is therefore acting with reckless disregard for Bob's life? Did Alice move to block the safe path knowing what effect it would have on Carlie's bullets? Did Dave mislead Charlie and/or Alice into acting with the intent of killing Bob?