http://kxan.com/2014/06/29/cppd-son-in-law-accidentally-shot-man-outside-gun-show/
This is surely a tragedy. The SIL had to have violated 3 of the 4 rules for this to have happened.
Muzzle awareness and trigger discipline were not followed and it ended in death.
Check the comments
http://kxan.com/2014/06/28/man-shot-killed-outside-cedar-park-gun-show/