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“I have always been fascinated by the forensic sciences, especially the procedures and protocols involved in criminal investigations and catching the bad guy.”

In her third year of Psychology Marijn took a class on psychology in legal contexts with Dr Rachel Zajac. She found the class was a perfect combination of her passion for Psychology and her childhood interest in justice and the legal system.

“We learned about factors that influence how jurors make their decisions, why eyewitnesses are some of the least reliable sources of information, and how people can confess to crimes they did not commit. Of particular interest to her was the revelation that forensic investigators are nowhere near as perfect as she once thought! They make mistakes, and unfortunately this can - and has - resulted in many wrong convictions and miscarriages of justice.”

Marijn undertook a PhD in Psychology with the hope that she could aid forensic investigators in improving how they function, and reduce the likelihood of errors because every mistake can have severe consequences. Her research looks at factors that increase the risk of forensic investigators coming to the wrong conclusions, and what can be done to prevent this from happening in the future.

“Recent research has shown that many forensic investigators, including fingerprint analysts, DNA analysts, bloodstain pattern analysts, and even handwriting analysts, are vulnerable to making biased judgments when they’re exposed to additional information about a case. For example, the knowledge that the suspect has confessed can make the fingerprint analyst more likely to conclude that a fingerprint found at the scene also belongs to the suspect, even if that is the wrong conclusion.”

Dr Rachel Zajac and Marijn are currently involved with a project funded by the National Institute of Justice (NIJ) in the United States where they work directly with forensic examiners to address the problem of knowledge of additional information and how it can influence the perception and interpretation of forensic evidence.

“Despite an increased awareness that forensic investigators are influenced by case information, hardly anyone is trying to develop procedures that remain reliable even when an investigator has been exposed to additional information. One easy suggestion is to simply not give investigators information that could potentially influence them, but due to the nature of forensic investigations, that is not a viable solution. The main goal of the NIJ project is to develop and test several strategies that control for exposure to additional information. I think that it is very important to do what we can to protect forensic examiners
from external influences and to help them do their job properly.”