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Researchers supported by the Swiss National Science Foundation have analyzed how sadistic sexual murderers assaulting child victims commit their crimes and discovered a number of specific patterns. A better understanding of these crimes may help police in their investigations.

Sexual homicides involving are often highly publicized. These events are traumatic for the public, especially while the offender remains unidentified and not sentenced. Moreover, the prosecution of these cases is complex, lengthy and expensive.

With support from the Swiss National Science Foundation (SNSF), Julien Chopin, a postdoctoral researcher and criminologist at Simon Fraser University in Vancouver, examined an as yet unexplored aspect of these homicides: sexual sadism.

Access to police data

In his study, published in the Journal of Interpersonal Violence, Chopin highlights patterns associated with these homicides. His insights have practical application: "Our study provides new knowledge to police that can help them to reconstruct the sequence of events even when the evidence present at the scene of a crime is confusing", he says. The findings may also contribute to the search for relevant profiles, to identification of suspects and to their possible arrest. "They show also that we cannot continue to blindly apply what we know about cases involving adult victims to the specific case of crimes committed against children", says Chopin.

Exploiting clues from the crime scene

The researchers pointed out that crimes of sexual sadism committed against children have unique characteristics that distinguish them from both crimes of sexual sadism committed against adult victims and conventional sexual crimes committed against children.

The study shows that there is a certain logic to the way offenders plot their crime. They think about it and plan it at length. "They target areas of predation and children or teenagers who are unsupervised, for example while riding their bikes or hitchhiking. They use subtle ruses to lure the children. They commit their crime in isolated places so as not to be noticed", says Chopin.

These crimes have other special characteristics: the sexual acts are varied and extreme, death occurs by strangulation or asphyxiation, and victims are often left naked. "Since they may be recidivist offenders, it is in the interest of the police to systematically collect clues at the scene of the crime and compare them with their databases", Chopin adds.

Systematically analysing the offender's modus operandi

Thanks to the collaboration of the police, Chopin and his colleague Eric Beauregard, professor of criminology at Simon Fraser University in Vancouver, had access to all the extra-familial sexual homicides that occurred in France and Canada between 1948 and 2018. With this information, they created one of the most extensive international databases on sexual . A key feature of this database is that the dataset is sufficiently large to allow for statistical analysis. It includes 772 cases, of which 136 involve victims classified as children—i.e. under 16 years of age.

To determine which of the cases had sadistic features, the researchers developed a scale based on eight criteria relating to what can be observed at the , for example evidence of sexual mutilation or sexual domination. Each criterion was assigned a value, either 0 (not present or unknown), 1 (perhaps present) or 2 (present). The combination of criteria results in a diagnosis of sexual sadism when the score is at least 6. Of the 136 cases of child sexual homicide in the researchers' database, 35 were identified as sadistic crimes (mean score 6.97) and 101 as conventional crimes (mean score 2.69).

For each of the 136 cases, the scientists then analysed the offender's decision-making process before, during and after the crime. They studied 34 variables using statistical models: 6 for the context of the crime, 3 for the location, 6 for the characteristics, 14 for the method of killing and the body recovering characteristics and 5 for the strategies used by the offender to avoid being identified. They were thus able to identify the main characteristics of sadistic sexual child homicide.

More information: Julien Chopin et al. Sexual Sadism: Its Role in the Crime-Commission Process of Sexual Homicide of Children, Journal of Interpersonal Violence (2020). DOI: 10.1177/0886260520916844

Journal information: Journal of Interpersonal Violence