The Weekly Reflektion 28/2022

Convicting a criminal of a crime is the goal of police investigations. During the investigation the evidence has to be looked at objectively. This is not always the case as the police, being human, are influenced by many factors and biases. Justice is not always done.

How do you avoid confirmation bias in your investigations?

Marius Kolstad, a former Norwegian bodybuilding champion, was found murdered on March 24, 1999. The case was without a suspect for a long time, and the media pressed hard for a solution. One year later, Stein Inge Johannessen was arrested and charged with murder. The basis was a statement from one of Kolstad’s neighbours, who claimed to have seen Johannessen leaving the scene of the crime, his clothes spattered with blood. Johannessen claimed that it was not him the neighbour had seen and denied all involvement with the crime. It was his word against the eyewitness’s word.

The police, under pressure to solve the crime, chose to believe the eyewitness and so began the task of building a case against the accused man. Once the mental model has been established the search began for evidence to confirm the only theory the police had. Equally important was to explain how any evidence that did not support their theory could be rejected.The accused was held in custody for nine months, all the time protesting his innocence. Four days before the case was due to come to trial, another man arrested in a non-related case confessed to police that he had killed Marius Kolstad. 

Confirmation bias is normal and is a process that is in play with all of us in decisions we make. We tend to build a mental model and then look for information to confirm this mental model. When this happens in a police investigation, the consequences can be very serious for the people involved. Details that are neutral and are neither for nor against our theory are accepted as confirmation of our view. The most concerning issue is that we as humans tend to explain awayalternative models, and not look for information that contradicts our perception of how the world is connected.

In our world of Major Accident prevention and incident investigation it is important not to limit your hypotheses concerning what happened during an incident, and why it happened. Consciously keep an open mind so that the evidence logically leads to a conclusion, rather than lookingfor the evidence you need. This approach will also influencehow you ask questions in the witness interviews. 

In your operation do you jump to conclusions about what happened and why, possibly missing opportunities for learning? Do you take measure to combat this confirmation bias?