A serial killer is an individual who murders three or more people, with the killings taking place over a period of more than one month in three or more separate events. The Federal Bureau of Investigation (FBI) states that the motives of serial killers can include anger, thrill-seeking, attention seeking, and financial gain, 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 have a variety of personality disorders. They 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 among them.