Facebook Killers: The Six Types Revealed

Reactors - who murder a person who posted something they object to online - are the most common killers linked to the network.

Researchers have identified six ways in which Facebook tends to be used in murder cases.

They described the most frequent type as "reactor", where the perpetrator of a killing reacts to information posted on Facebook by attacking the victim offline. This accounted for 27% of all murder cases involving Facebook.

In 2008, for example, Wayne Forrester killed his wife Emma in Croydon, after reading Facebook posts claiming they had split up and that she wanted to meet other men.

The next most frequent category is "informer", which accounts for 22.9% of cases. Here, perpetrators used Facebook to tell their friend network about homicidal intentions or a murder they committed.

Last year, Colorado man Merrick McKoy stole his two-year-old daughter from his ex-partner.

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He posted photographs and messages on the site, including the post: "I told u I can’t live without u lol u thought I was joking now me n Mia out this b****." He later shot his daughter, then himself.

The next most common category was "antagonist", where hostile exchanges on the social networking site led to fatal face-to-face confrontations, accounting for 16.7%.

The other three types identified by the researchers are "fantasist", where murderers used Facebook to indulge in fantasises, "predator", where criminals created a fake profile to lure victims to their death, and "imposter", where perpetrators impersonated someone else on Facebook - either the victim, to maintain the illusion that they were alive, or another person, to gain access to the victim's Facebook profile.

However, the researchers concluded that the term "Facebook murder" was not a meaningful one, and could be harmful in understanding the complex and varied nature of killing.

They wrote: "The cases we identified were not collectively unique or unusual when compared with general trends and characteristics - certainly not to a degree that would necessitate the introduction of a new category of homicide or justify a broad label like Facebook Murder."

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The researchers - Elizabeth Yardley and David Wilson of Birmingham City University - examined 1,000 reports of "Facebook murder" globally, based on media accounts of convictions for  offences including murder, manslaughter and culpable homicide.

They also found that Facebook murders, compared with general murder trends, tend to disproportionately affect younger people, that women are over-represented as victims, that there was a higher proportion of murder-suicides, and that those involved came from a broader socio-economic range.

The researchers did not study any other social networks.

They also said that the appearance of Facebook in cases was "not particularly surprising" because "a close social relationship between victim and perpetrator is a well-established characteristic of this type of crime and such relationships are increasingly likely to be displayed and performed on (social networking sites)."