« We came face to face but he didn’t shoot. What did he look like? An ordinary guy with a Kalashnikov » (witness account, Le Bataclan, November 2015).

« He was like a random guy holding a Kalashnikov. That’s all. » (Julien Pearce, radio reporter, Paris, November 2015).

The transformation of groups of previously nonviolent individuals into repetitive killers of defenseless members of society has been a recurring phenomenon throughout history and continuing at the present era. This apparent transition of seemingly normal, “ordinary” individuals, to perpetrators of extreme atrocities is one of the most striking variants of human behavior, but often appear incomprehensible to victims and bystanders and in retrospect even to the perpetrators themselves and to society in general. This transition is characterized by a set of symptoms and signs for which a common syndrome has been proposed, Syndrome E , as well as a pathophysiological model (Fried, Lancet, 1997). A summary of last year conference and a survey of the syndrome manifestation in the current era will be presented.

The above witness accounts coming face to face with the perpetrators in 2015 Paris, highlight our central questions. Who are these “random” guys? Why and how do “ordinary guys” become mass murderers? As we ponder these questions, I will present the main challenges for this second Paris conference on “The Brains
that Pull the Triggers”. Several sets of questions will be highlighted:

1. What can neuroscience tell us about the mechanisms that may underlie the
transformation of seemingly normal individuals to mass murderers?

2. Can we find partial or parallel manifestations of the syndrome in psychopathology or sociopathology? Does a categorical diagnosis such as DSM have value –descriptive, predictive, preventive- or are alternative approaches feasible?

3. What are the mechanisms of group contagion and propagation in the present
era?

4. Is scientifically-based intervention feasible?