The author discusses an alternative-prediction scheme to typological profiling in addressing the imminent threat of chemical weapons/biological weapons (CW/BW) use among terrorist and rogue-state groups. Although profiling may be useful in capability analysis and the early identification of potential perpetrators, it fails to predict the actual sequential development and construction of a CW/BW terrorist event. Similar to the behavior of the perpetrator and victim in cases of interpersonal violence, predictive patterns of CW/BW use emerge in a study of the behavior of terrorist groups or rogue leaders accused of using such weaponry. Due to the requirements of preparation involved in CW/BW weapons development and use, patterns of predictive behavior occur over months or years prior to actual use. Citing the "lethal violence sequence" as a unit of study, the author discusses features of group baseline, preconflict, lethal event, and recovery behavior that often accompany such attacks. Similar to other acts of genocidal killing during war-time, group history regarding religious fundamentalism and ethnic dislocation, indiscriminant target selection, and hiding of evidence become positive predictors of chemical weapons use by terrorists. Victim and contextual contributions are also described for each phase of the lethal violence sequence. Following the use of a case vignette to illustrate the CW/BW lethal violence sequence, the author presents recommendations for intervention in the CW/BW lethal violence sequence. The recommendations pertain to actions that can be taken by individuals concerned about the threat of CW/BW use; law enforcement officials and Federal antiterrorist agencies; manufacturers and industries involved in large export sales of heavy equipment, aerosol generators, refrigeration systems, and dual-use chemicals and vaccines to countries suspected of having CW/BW; and governments. 73 references