Recounting the cases of such notorious criminals as the Hillside Strangler, Son of Sam, Ted Bundy, Richard Speck, the Boston Strangler, Charles Manson, and Wayne Williams, the authors construct a profile of the kind of person who commits mass murders. They contend that the typical serial killer travels around, sometimes from State to State, searching for victims to rape, sodomize, torture, and kill. Few serial killers are driven by delusions or hallucinations and are not medically or legally sick. Rather, the serial killer is typically a sociopathic personality who lacks internal control and has an excessive need to control and dominate others. The serial killer knows right from wrong but simply does not care. His or her target usually involves innocent strangers who have certain physical features or may just be accessible. Not all sociopaths, however, commit murder; most are bound by external controls, especially family and community pressures. The authors examine the motivation of mass murderers and note difficulties police officers encounter in capturing them. Endnotes, figures, and photographs