The answer is easy.
This crime was not caused by guns.
It was caused by parents who failed to recognize that they had a very sick kid, but who now dodge their responsibility by blaming guns.
Whether they failed due to incompetence or due to a lack of will is not known, but they failed.
Posted the above before i read all of the comments, so I retract part of it.
Parents tried, cops blew it.
Old story. Cops are for “post crime action.”
Nothing takes the place of your ability to protect yourself.