Decades ago in NYC, Bernie Goetz went to jail on gun possession charges even though a jury refused to convict him for shooting his assailants.
The powers-that-be wanted to get him SO badly they gave immunity from prosecution to the perps who tried to rob him in order to get them to testify against their victim.
I don't remember all the details, but Bernie didn't do himself any favors by opening his mouth afterwards. In the OP, maybe the guy being charged SHOULDN'T have called 911 and just walked away.