Fingerprints appear to contain valuable information about the exact actions that took place during a crime.

At present, fingerprints are mainly used in forensic research to identify the perpetrator of a crime. But there is much more that can be solved with it, as Anouk de Ronde, who is affiliated with the Amsterdam University of Applied Sciences, discovered. Such fingerprints can contain crucial information about the acts performed at a crime scene. And that means that, thanks to fingerprints left behind, we can gain even better insight into exactly what happened during a crime.

Fingerprints and actions

When you think about it, it actually makes sense that fingerprints contain information about actions that have taken place. Yet this has never been researched before; De Ronde is therefore the first in the world to bite into this matter. “At the same time, this means that such information is not yet commonly used in court,” she says in conversation with Scientias.nl. “And I hope that with the help of my research, those possibilities will improve.”

Unique method

De Ronde developed a unique method with which fingerprints in criminal cases can be analyzed even better in the long term. “During the study, we identified several variables that provide information about the activity that took place,” she explains. “For example, the exact spot where you left your fingerprint on an object may provide information about which activity you performed. The direction of the fingerprint or the chance that you transfer a trace can also differ between activities. And this information can be used to provide information about the actions that may have taken place.”

Experiments

De Ronde draws this conclusion based on experiments it conducted over the past four years. “We have conducted experiments with letters and knives, among other things,” she says. In the letter experiment, we looked at the location of the fingerprints on the object, in order to determine whether the letter was written or read. In the knife experiment, we looked at whether we can extract information from the part of the hand that ends up on the knife in a certain place and whether this might reveal whether a slice of gingerbread was cut with the knife or whether the knife was used for stabbing. ” The actions were filmed and the fingerprints were made visible with the chemical cyanoacrylate. De Ronde translated the measurement data into a mathematical model, which can be used to predict which action was most likely to have taken place.

Pillow experiment

But it didn’t stop there. De Ronde also asked visitors to the Lowlands festival to make up a pillow or ‘smother’ a doll with it. “The participants were given finger paint on their hands so that we could immediately see the locations of the fingerprints on the cushions,” says De Ronde. “We then developed a model based on pillowcases from this experiment. Based on the location of the fingerprints on the pillowcase, this model can predict which activity is likely to have been performed with the pillow. This model proved to work very well; in 98 percent of the cases, the model predicted the correct activity.”

Although that is of course a great result, there is still work to be done to translate this to the real world. “The latest results are based on paint traces,” emphasizes De Ronde. “Further research should show whether the results of the model are also reliable for fingerprints that are made visible with the regular visualization methods used in forensic investigations.”

Good start

All in all, the work is a good start to perhaps a crucial part in criminal cases. Because if fingerprints can indeed tell more about the exact actions that have taken place at a crime scene, it could make the work of the police a lot easier. In any case, the first results are promising. “This research shows that fingerprints do indeed contain valuable information about the activities that took place,” concludes De Ronde. “This is information that is still little used in court today. As mentioned, fingerprints are mainly used to determine who left the trail. However, the question in court is increasingly changing to ‘how did the railway get there?’ and in cases where these kinds of questions arise, my research can be of great importance.”

But we’re not there yet. For example, it remains to be studied whether fingerprints in combinations of actions – such as first smothering with a pillow and then neatly making up the pillow – can also reveal important information. “This research is a first, exploratory study,” emphasizes De Ronde. “In order to actually be able to use this information in practice, further research is needed into how fingerprints behave during different actions.”