Researchers and policymakers have supported a public health approach to countering violent extremism throughout the War on Terror. However, barriers to obtaining primary data include concerns from minority groups about stigmatization, the ethics of harming research subjects by exposing them to violent content, and restrictions on researchers from institutions and governments. Textual analyses of declassified documents from government agencies may overcome these barriers. This article contributes a method for analyzing the predisposing, precipitating, and perpetuating factors of terrorism through open source texts. This method is applied to FBI interrogation summaries of Al Qaeda terrorist Umar Farouk Abdulmutallab who attempted an attack aboard an airplane in 2009. This analysis shows that consuming militant content online led him to narrow his social relationships offline to extremists and foster identifications with subjugated Muslims around the world. After deciding to wage militancy, loyalty to Al Qaeda members, swearing allegiance to and obeying group leaders, and interpreting religious texts militantly perpetuated violent activities. Such work can advance empirical work on militant behavior to develop interventions.