They analysed cases of homicide in which the social networking site Facebook had been reported by the media as a significant factor.
They found 48 cases of "Facebook murder" from around the world between 2008 and 2013 and identified six different types of killers. They are reactors, informers, antagonists, fantasists, predators or imposters.
A reactor reacts to content posted on Facebook by attacking the victim face to face, researchers explained.
The informer uses Facebook to inform others that they intend to kill the victim, that they have killed the victim, or both.
Informers use Facebook as a way of demonstrating their control over the victim and the situation.
An antagonist engages in hostile exchanges on Facebook that escalate into face to face violence. They may seek to introduce a physical advantage when the conflict goes offline through arming themselves with weapons.
A fantasist uses Facebook to perform or indulge in a fantasy. For fantasists, the line between fantasy and reality has become increasingly blurred and the homicide may be a way of maintaining the fantasy or preventing others from discovering the deception.
A predator creates and maintains a fake profile to lure a victim and meet them offline. They may draw upon the information available on the victim's profile to exploit vulnerabilities to establish grounds upon which to develop a relationship.
An imposter posts in the name of someone else. This could be the victim in order to create the illusion they are still alive or another person to gain access to and monitor the victim's profile.
The researchers, however, urged that social networking sites should not be blamed for these crimes. The study was published in the Howard Journal of Criminal Justice.