Well, there is one fact known - in a training environment a real bullet came out of a gun and killed a person.
The officer might have been handed a pistol that wasn’t his but I was always taught - when handed a weapon treat it as loaded and check/clear it.
If it was his weapon - he belongs in jail.
While the number of these shootings are rare they have happened enough for trainers to adopt a whole list of safety measures when conducting force on force training.
Every body from the OIC, RSO,s to the instructors failed to do their jobs I would think that a lot of heads should roll over this shooting.
Making sure the safety protocols are followed is every ones responsibility from the person in charge to the persons actually doing the training.
Besides the officer who did the shooting there are or should have been others that should have prevented this