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Behavioral Study of American "Homegrown" Terrorist Offenders

NCJ Number
Date Published
October 2018
2 pages

Based on an examination of forensic biographies of 135 American jihadism-inspired "homegrown" terrorists, this NIJ-supported study provides a broader understanding of the signs and symptoms of radicalization and may assist law enforcement agencies in developing better assessment protocols for intervention programs.


One key study finding is that a common precursor to radicalization is new-found religious fervor, accompanied by a desire to connect to like-minded individuals or the creation of cells of believers, which includes converting family members or friends to the jihadist cause. Although initial contact with jihadist beliefs may be through the internet, interaction with peer believers drives the intensification of radicalization. Radicalization was commonly preceded by public expressions of a commitment to action, either by going abroad to fight or by taking some action in the United States. Radicalization generally evolves over several years, although the pace of radicalization has increased since 2010. Four recommendations are offered for countering the radicalization process. First, it is feasible to develop a dynamic risk-assessment protocol that focuses on tracking progressive extremism. This will be more reliable than unstructured protocols in anticipating the imminent risk of violent behavior. Second, develop programs that inform families of early warning signs of growing radicalization. Third, local law enforcement agencies should develop outreach programs for Muslim community organizations and mosques. Fourth, programs for countering violent extremism should be developed for middle school and high school students and staff.

Date Published: October 1, 2018