the differentiation of serial, mass, and spree murderer," later elaborating that spree killers "engage in the killing acts for days or weeks" and the "methods of murder and types of victims vary". Andrew Cunanan is given as an example of spree killing, while Charles Whitman is mentioned in connection with mass murder, and Jeffrey Dahmer with serial killing.

In 2005, the FBI hosted a multi-disciplinary symposium in San Antonio,