HS Turku Finnish researcher got involved in developing a tool for chasing serial killers – This is the “psychological fingerprint” that could be helpful in Finland as well

Serial killer it is possible to link the offenses on the basis of the perpetrator’s behavior at the crime scene. This is the opinion of a legal psychologist and a dissertation researcher at Åbo Akademi University Tom Pakkanen, 44. He is involved in a study that created a tool to identify serial killings. Finnish and Italian researchers are involved.

The study looked at 116 homicides in Italy, which fell into 23 different categories. The cases ranged from 1970 to 2001. The material is Italian because there was not enough suitable material for research in Finland.

“The tool makes it possible to analyze the behavior of the perpetrator at the crime scene. Attention is paid, for example, to the victim’s injuries, what kind of weapon the perpetrator has used or whether an attempt has been made to clean the crime scene, for example by burning, ”Pakkanen says.

When all the observations of behavior are bundled together, a combination is created, which Pakkanen calls the criminal’s psychological fingerprint. This combination of behaviors can be compared to other homicides and assessed whether the case under investigation could be part of a series of murders.

It is not worth comparing individual behavioral traits.

“If crimes are searched only on the basis that a knife has been used in the act, then quite a few homicides would be found in Finland,” Pakkanen illustrates.

Psychological fingerprint In Pakkanen’s opinion, it could be used as an aid in the police’s preliminary investigation work. However, in its current form, the tool is not suitable for use in Finland. This is because the tool was developed with Italian material.

“There are indications that psychological fingerprints may look a little different in different cultures,” Pakkanen says.

According to Pakkanen, another problem is that there is no database of serious violent crimes in Finland that would allow a comparison of psychological fingerprints between different crimes.

In any case, Pakkanen believes that in Finland, a psychological fingerprint would fit better in the investigation of serial burglaries, sexual offenses and car theft. There are more of them in Finland than serial murders.

Thought According to Pakkanen, there are two assumptions that a serial killer behaves in the same way in different crime scenes.

“The first is that a person behaves enough in the same way from time to time. This idea comes from personality psychology, which thinks there is a certain persistence in behavior that is observable. Of course, the behavior is influenced by the current situation, the victim’s behavior and many other things. ”

“The second starting point is that there is enough difference in behavior between the different factors and they can be distinguished from each other,” says Pakkanen.

According to him, it would seem that in the behavior of criminals, the things over which they themselves are able to influence are repeated. According to Pakkanen, this is illustrated, for example, by the way the serial killer approaches the victim: does he use the victim with violence or does he use charm and override the victim’s journey.

seamless tool there is no psychological fingerprint. However, according to Pakkanen, the studies have given good results with strong resolution.

“For each analysis, the strength of the link between the cases and the margin of error can be presented. It would be up to the court to assess what is a sufficiently unique psychological fingerprint and whether it has probative value. ”

Pakkanen identifies so-called copy cat criminals as one possible source of error in the tool, ie people who imitate crimes in public. In these cases, the reliability of the analysis is affected by how much the imitator actually knows about the crime he or she is imitating.

“This is one reason why the psychological fingerprint is just a tool to support the investigation. Other investigation and evidence is required to verify that the link created by the tool between the different cases is correct. My own position is that a psychological fingerprint could be presented as evidence in court. ”

Dissertation related to Frost’s psychological fingerprint Crime Linking in Serial Homicide – Towards Practical Application presented for public examination at the Faculty of Humanities, Psychology and Theology of Åbo Akademi University. The dissertation will be held on Friday, March 18, 2022.