From one article I read:
As a police officer was trying to remove the bullets to make the weapon safe, he accidentally discharged the gun once. The bullet struck the floor. No one was injured.
So, was
he trying to remove the bullets by firing them? As I recall, you unload that revolver by pushing a button the lets the cylinder swing to the side, well out of range of the firing pin. I wonder if he knows the button from the trigger.