Serial murder is defined for this study as “the premeditated murder of three or more victims committed over time, in separate incidents, in a civilian context, with the murder activity being chosen by the offender.” The definition includes health care workers who murder their patients, parents who murder their children, professional assassins who operate under the confines of organized crime syndicates and persons who kill multiple spouses/lovers. Although male and female serial murderers shared similar backgrounds, there were more differences than similarities between the two groups. Female serial murderers did not generally stalk or torture their victims and usually used poison to kill. Most killed close to their home or workplace rather than displaying the mobility of many male serial killers. Further examination of this difference might help law enforcement officials identify serial murders that had previously gone undetected, particularly in hospitals and within families.