Cop reaches for taser, draws gun by mistake and shoots unarmed suspect, but no charges filed

I'll bet you thought this was a dupe, but it isn't.

Thanks to Accept the Challenge.

This previous incident happened in California. The suspect was handcuffed in the back of a patrol car. The LEO reached for a taser and came out with a handgun and shot the suspect. No charges filed.

Do you notice the important aspect that led to no charges being filed?