Mass murder is the result of the complex interaction of several factors. What seems ubiquitous within mass murder are extreme feelings of anger and revenge. Yet despite these intense affective states, mass murders are, as a rule, not behaviorally impulsive, but rather prepared. The presence of extreme hate and anger evokes an impulsive outburst of rage, whereas planning and premeditation point in the direction of a cognitive, rather unemotional deed. This inconsistency is also reflected in reports of offenders' emotional states during the execution of their crimes: while some mass murderers have been described as calm, focused and emotionless during the events, others have shown signs of hostility, confusion, and distress. Considering mass murder from the perspective of its violence mode might shed some light on its nature and dynamics. With respect to the differentiation between affective and predatory violence, Meloy (1988) developed a model for applied forensic practice. The fully documented case of mass murder discussed in this study contains nine indices of predatory violence and one of affective violence. Furious affects of hate and anger were present but appeared to precede the cold-blooded killings. As a matter of fact, it is argued that the offender carried out the predatory murder in order to alleviate the psychological tension and symptoms generated by these severe ego-dystonic affects. The offender thus didn't seem to strive for narcissistic gratification of omnipotence, but rather seemed to aim to solve a problem. Copyright © 2011 John Wiley & Sons, Ltd.