Question: what are the qualifications of a serial killer

title: Serial killer
text: Kelleher and Kelleher ( 1998 ) created several categories to describe female serial killers . They used the classifications of black widow , angel of death , sexual predator , revenge , profit or crime , team killer , question of sanity , unexplained , and unsolved . In using these categories , they observed that most women fell into the categories of black widow or team killer . Although motivations for female serial killers can include attention seeking , addiction , or the result of psychopathological behavioral factors , female serial killers are commonly categorized as murdering men for material gain , usually being emotionally close to their victims , and generally needing to have a relationship with the victim , hence the traditional cultural image of the `` black widow . '' In describing murderer Stacey Castor , forensic psychiatrist James Knoll offered a psychological perspective on what defines a `` black widow '' type . In simple terms , he described it as a woman who kills two or more husbands or lovers for material gain . Though Castor was not officially defined as a serial killer , it is likely that she would have killed again .