So researchers have begun exploring more subtle factors, like crime, pollution and family support.
"Make no mistake, there was nothing isolated or subtle about the crime these people committed," said Mr. Pesquera of the F.B.I.
All it takes to make a massacre in such a place is to add a militarized national police force that is led by political cronies and untrained in the subtler forms of crime fighting.
And while some authorities have extensive contact with their registered offenders (Illinois has special monitors who follow those deemed most dangerous for life, looking for even subtle signs of crimes), those in some other states spend little time with offenders once they have filed an address.
Bennett Miller's third feature film, after Capote and Moneyball, and for which he won the Best Director award at last year's Cannes festival, is a subtle and subdued true-crime drama that doesn't fully let on what it's about until after it ends.
Her crime studies are subtle, mysterious affairs that never turn out quite the way you anticipate.
It might sound like an unlikely combination, but Phil Rickman's unique crime series is subtle, atmospheric and haunting.
Faith Healer is, in part, a thriller, whose boundaries are so subtle and slippery that the crime could almost be missed.
Ms Strong added: "If we just always try to make it look like a certain type of perpetrator it actually takes away from the fact that the crime is more subtle than that.
Trump's not-so-subtle linking of immigrants to crime, if taken seriously by black people, could also serve to divide the African American and Latino communities, who face some of the same prejudices and challenges in America and have every reason to reject Trump.
