If the police cant stop mass killings when they have the name of the killer before, the police are useless.Why in the heck would you say such a thing?https://www-m.cnn.com/2019/08/07/us/el-paso-crusius-gun-warning/index.html
As usual there were tips in place to law enforcement who were felt it more important not to miss their meeting at the donut shop.
CIAO
Your linked article explains the call, and your evil stoking comment is the problem with the world today...
The police don't prevent crimes, they clean up afterwards and punish the criminals.