Many politicians are quick to point to the shooters' disturbed minds. News reporters probe for "loner" tendencies or signs of instability.
“Mental illness and hatred pull the trigger. Not the gun,” said President Donald Trump on Monday, after two mass shootings in less than 24 hours.
Some mass shooters have a history of schizophrenia or psychosis, but many do not. Most studies of mass shooters have found only a fraction have mental health issues. Researchers have noted a host of other factors that are stronger predictors of someone becoming a mass shooter: a strong sense of resentment, desire for infamy, copycat study of other shooters, past domestic violence, narcissism and access to firearms.