People with an agenda usually blame cultural stereotypes of black men for why white police officers mistakenly shoot unarmed black suspects more often than white ones during computer  simulations. 

There's just one problem; psychology undergraduates in simulations do the exact same thing. New research points to another factor: how individuals view threats from outside groups, independent of culture or race. Across two studies, participants with strong beliefs about interpersonal threats were more likely to mistakenly shoot members of outside groups versus members of their own groups. 

So fellow psychology students are safe.  Except in grad school, where James Holmes can be turned down by a gun club because he was too weird but no one in the neuroscience graduate department felt he was too dangerous to hang around.(1)

Citation: Saul L. Miller, Kate Zielaskowski and E. Ashby Plant, 'The Basis of Shooter Biases: Beyond Cultural Stereotypes,' Personality and Social Psychology Bulletin, forthcoming, October 2012 doi: 10.1177/0146167212450516

NOTE:

(1) A psychiatrist on the 'threat' team did report on his bizarre behavior but like a good academic bureaucracy they did nothing and are now scrambling to explain it. Statistics show that gun club members, and people with CCW permits, know exactly how to deal with weird people who get dangerous with guns.