The guy had a drug conviction and failed drug tests, a felony conviction, he was out on probation ... you can't hardly get any more prohibited than that, now can you?
He still managed to get his hands on a gun and injure multiple police officers, killing one of them.
You can look at this in a multitude of ways:
-It's too easy for criminals to get guns
-Some people get released from prison when they shouldn't be.
-The law prohibiting him from owning a gun was not enforced
Either way, we need to mend our ways.