The Crime and the Criminal
He threatens many that hath injured one.
Fall of Sejanus, act 2
The terms mass murderer and serial killer are often used interchangeably, and incorrectly, by Americans. These terms convey very different concepts to the criminologist or behavioral scientist, even though their distinctive characteristics are frequently lost in casual conversation. The act of mass murder describes a crime in which multiple individuals are slain by a perpetrator in the same incident, or closely related episodes of violence. On the other hand, serial killing defines a crime in which a number of individuals are slain over a protracted period of time which may range from a few months to many years. Each murder committed by the serial killer is a discrete criminal act which is followed at some later time by yet another discrete crime, even though the perpetrator's method of operation may remain constant.
The period of time during which the murderer is not criminally active is known as a cooling-off period. The serial killer will usually experience a cooling-off period that may last days, weeks, or even months, during which he fantasizes about his crime and plans for (or selects) his next victim. This period of quiescence is a primary element that differentiates the serial killer from other murderers who claim multiple victims. 1 On the other hand, the mass murderer typically commits his mayhem in a single incident or (rarely) in a cluster of closely related incidents in which multiple individuals are slain. If the murderer