Could law enforcement officials have done more to prevent it?
The painful and inevitable question has frequently dogged the police after shootings. Experts say that most mass shooters display warning signs before becoming violent, and officials have often received tips, calls or reports about concerning behavior, sometimes long before someone picks up a weapon.
But law enforcement officers, at least under traditional police training, are limited in what they can do in response. If a crime has not been committed or a subject does not meet the criteria to be sent for an involuntary mental health evaluation, the case is often closed.
Full story: Can Police Prevent a School Shooting If a Threat Is Not a Crime? – The New York Times