1. A number of victims are slain over a comparatively short span of time, usually hours, less often, days.

2. If the killings are committed in more than one location they are part of a ‘continuous’ action.

3. Victims are typically either selected at random and attacked or not on the momentary whim of the killer; or form part of a target group - again often arbitrarily chosen as ‘scapegoats’.

4. The killer frequently concludes his spree by taking his own life (though this may take the less obvious form of behaving so recklessly that armed law enforcement officers are obliged to shoot to kill.)

5. A Mass Killer usually attacks with a semi-automatic weapon.

6. The attack is usually made at a school, university or restaurant.

1. Killings are separate (‘serial’), occurring with greater or less frequency, often escalating over a period of time, sometimes years, and will continue until the killer is taken into custody, dies, or is himself/herself killed.

2. In common with ‘normal’ homicides, killing tends to be one on one.

3. There is no (or very little ) previous connection between the perpetrator and the victim, the persons involved rarely being related.

4. Although there may be a ‘pattern’, or ‘victim’ trait, individual murders within a series rarely display a clearly defined or rational motive.

5. An increasingly greater spatial mobility (since the advent of the automobile) has enabled killers (if they wish) to move rapidly from one place to another, often before a murder has been discovered.

6. There is usually a high degree of redundant violence, or an ‘overkill’, where the victim is subjected to a disproportionate level of brutality.

7. Serial Killers usually stab or strangle their victims although some have been known to shoot their victims.