Nation Family said Colorado suspect had ‘mental illness.’ Experts say that’s rarely the cause of mass shootings. March 25, 2021March 25, 2021Ryan W. Miller, USA TODAYComments Off on Family said Colorado suspect had ‘mental illness.’ Experts say that’s rarely the cause of mass shootings. For years, mass shootings have been blamed on a gunman's mental illness. Experts say that characterization is usually wrong.