A serial killer is typically a person who kills three or more people, with the murders taking place over more than a month and including a significant period of time between them. The Federal Bureau of Investigation (FBI) defines serial murder as "a series of two or more murders, committed as separate events, usually, but not always, by one offender acting alone". Identified serial killers Unidentified serial killers This is a list of unidentified serial killers who committed crimes within the United States. See also List of rampage killers in the United States List of mass shootings in the United States International: List of serial killers by country List of serial killers by number of victims References Bibliography serial united states Ser