IntroductionMass murder is defined by the FBI as the killing of three or more people in a single event or on the same day (Petersen & Farrington, 2007) . Mass murderers are complex and can be examined by the many factors that regularly appear among them, such as the violence triggering the events, the weapon of choice, and mental illness. The motivations and methods used to commit mass murder fall easily into specific groups, and through examining these definitions and specific cases, there is much to learn about the mind of a mass murderer .HistoryThroughout history, mass murder has not been a problem for people on the same level and in the same sense as it is today. A related event observed in history that can be studied for its similar preparation and organization is genocide. Genocide, an international crime, is a form of large-scale mass murder, in which many people are killed in a series of unrelated events due to prejudice or war (Reisman, 2008). Killing a large group of people requires a high level of organization. The logistics of how to do it, where to do it, and where to dispose of the bodies, among other things, must be considered before the killing begins (Reisman, 2008). The only similarity to the 21st century version of mass murder is the predatory violence involving extensive planning and little or no emotion involved in the killing (Meloy et al., 2004). However, other than that, it is difficult to compare the two events because genocide results in many deaths and can take place over long periods of time. For example, during the Holocaust, Nazi Germany systematically exterminated millions of Jews over a three-year period (Reisman, 2008). This trend is relevant due to the deaths of more than three p...... middle of paper ......control. American Behavioral Scientist, 52(10), 1447-1464. doi:10.1177/0002764209332557Hamamoto, D.Y. (2002). Empire of Death: militarized society and the rise of serial and mass murders. New Political Science, 24 (1), 105-120. doi:10.1080/07393140220122662Reisman, W.M. (2008). Act before victims become victims: preventing and stopping mass murder. Western Reserve Case Journal of International Law, 40 (1), 57-85. Retrieved from http://proxy.lib.clemson.edu/login?url=http://search.ebscohost.com/login.aspx?direct=true&db=aph&AN=34239668&site=ehost-liveWithout exception, privacy prevails on the duty to warn. , rules of justice (2004). Mental Health Law Report, 22 (6), 53. Retrieved from http://find.galegroup.com/gtx/infomark.do?&contentSet=IAC-Documents&type=retrieve&tabID=T003&prodId=GRCM&docId=A120474886&source=gale&userGroupName=clemson_itweb&version=1.0