FBI Criteria for Distinguishing Between Mass, Spree and Serial Homicide

 

Requirement:

(1) single perpetrator or a single group of perpetrators

(2) some degree of premeditation before each event

 

Parameters:

(1) number of victims

(2) number of locations with assaults performed at one time

(3) number of events (delimited by an interval between homicides to allow for "cooling off")

Number of Victims	Number of Locations	Number of Events	Term
2	1	1	double homicide
3	1	1	triple homicide
>= 4	1	1	mass
>= 2	>= 2 (multiple)	1	spree
>= 3	usually >=3 (multiple)	>= 2	serial

 

where:

• A killing spree may go on for days or even weeks. The spree killer tends to continue to kill until caught or killed.

• A mass murder may be conducted against a group or a family ("family mass nurder").

• Murders could be excluded from the above classification if they are: (1) accidental, (2) done while intoxicated, (3) done for a motive such as profit

• A serial killer might kill a number of people at the same location over a considerable period of time.