A serial killer (also called a serial murderer) is a person who murders three or more people, with the killings taking place over a significant period of time in separate events. Their psychological gratification is the motivation for the killings, and many serial murders involve sexual contact with the victims at different points during the murder process. The United States Federal Bureau of Investigation (FBI) states that the motives of serial killers can include anger, thrill-seeking, financial gain, and attention seeking, and killings may be executed as such. The victims tend to have things in common, such as demographic profile, appearance, gender, or race. As a group, serial killers suffer from a variety of personality disorders. Most are often not adjudicated as insane under the law. Although a serial killer is a distinct classification that differs from that of a mass murderer, spree killer, or contract killer, there are overlaps between them. Source: Wikipedia (en)