I have just one questions: why after numerous mass shootings FBI failed to prevent the new one?
Profiling these retards is seemingly easy task, they don't use proxy, carry smartphones and have social problems. That latest schizo was very active online, leaving a trail of alarm signals. In additionally, he had firearms and obviously mental disorder. Just look at his face typical of paranoid schizophrenia.
But yes, first step should be IQ test for people buying firearms. In fact, US army requires IQ test and psychiatric assessment:
https://www.quora.com/Does-the-U-S-military-have-a-minimum-IQ-requirement-for-entryso why low IQ retards run around with guns?