The gun did not kill, the user did. A ‘straw’ buyer supplied the legally purchased gun to a criminal, who the used it to kill cops. How is the gun shop responsible? It ain’t. Better yet, have any of those directly involved been charged under federal gun laws? I bet they have not. For the safety of law enforcement, maybe a Justice Department Directive is needed that stipulates gun charges whenever a miscreant has a gun and commits a crime?