A police officer runs after a suspect. A threatening situation arises and the officer aims to shoot the suspect in the leg to stop him. However, he hits the suspect in the neck instead. Was this accidental or not? “The suspect was a person of colour, so it caused a major race-related dispute,” says movement scientist Bert Otten. Together with Mickey Wiedemeijer, he delved into the case at the time. Could their knowledge and expertise shed more light on what had happened? It is just one of the many examples Otten and Wiedemeijer speak about with enthusiasm. The two no longer work as ordinary movement scientists. They now help the police, as well as lawyers, to uncover the truth by studying a person’s movements. In the upstairs flat where Otten works, they are surrounded by computers, large screens, surveying equipment and various props such as a bowling ball and pieces of carpet. They use all of this to create 3D models and calculate speeds to determine, for example, whether an incident was a crime or an accident.
It all began about ten years ago, when the police approached the Department of Human Movement Sciences. A suspect in a robbery had a distinctive walk. Could the researchers do something with that? As (now emeritus) professor of neuromechanics, Bert Otten was immediately intrigued and involved Mickey Wiedemeijer, who had completed his degree under him. Together, they devised a way to map people’s walking patterns. Otten and Wiedemeijer filmed thousands of people on the street, “we’re allowed to do that, the police aren’t”, and used computer models to identify twenty characteristics that can be used to recognise someone’s way of walking. “We were then able to compare the footage of the robbery with images of a suspect who had been filmed walking in prison. This showed there was a very high likelihood that it was the same person,” Wiedemeijer explains.
“In all the cases we’ve worked on, our findings have never been contradicted by other evidence.”
Partly on the basis of their research, the suspect was eventually convicted. With emphasis on “partly”, Otten and Wiedemeijer stress repeatedly: a suspect can never be convicted solely on their evidence. “It can provide a helpful nudge in the right direction,” says Otten. “It’s supplementary evidence, or a reason to start or halt an investigation into a suspect. In every report we include a caveat and describe the most likely scenario.” Yet their results are often compelling. “In all the cases we’ve handled, our findings have never been contradicted by other evidence.”
Since that first case, things have moved quickly: Otten and Wiedemeijer now both work full-time on police cases. Lawyers also seek them out, for example in relation to traffic accident claims. “A lawyer came to us whose client had been hit by a car and could no longer work,” Otten recalls. “The collision had been filmed, and it looked like a minor incident. The lawyer asked whether we could determine if such an impact could cause whiplash. Using a model setup and our knowledge of vehicle dynamics, we concluded there could indeed be a relationship between the collision and his client’s symptoms.”
Such model setups are something Otten and Wiedemeijer frequently create. “Over the past thirty years I’ve developed software that allows me to simulate situations,” Otten explains. “But we need all the details of the situation.” This means you might find them at a crime scene measuring the street or mapping pavement patterns to ensure the correct proportions in the model. And that’s why Otten’s home contains bowling balls, scraps of carpet, toy cars and many other props. “We determine material hardness, calculate falling and bouncing forces, and then integrate all the information into a model. Comparing that with the facts and footage from the real situation allows us to determine what most likely happened.”
The two scientists greatly enjoy their new careers. “Every case is different, and we’re always keen to solve the puzzle,” Wiedemeijer says. “This work takes an enormous amount of time and is anything but nine-to-five, we sometimes speak to each other at the oddest times of day.” “But when you help break open a case that has completely stalled, that’s an incredible moment,” Otten adds. “In several cases where the police were completely stuck, we’ve managed to provide that Eureka! moment,” says Otten, referring to this article’s column. “I was even hugged by the head of the detective unit once, because they were utterly at a loss and our research led to the arrest of a suspect. Again, it involved someone with a recognisable gait, and the likelihood was very high that he was the same person seen on CCTV footage.”
Back to the officer mentioned at the start of the article. This too was a complex case in which Otten and Wiedemeijer invested an enormous amount of time. “We performed an extensive movement analysis on the CCTV footage and reconstructed the situation in real life,” Otten explains. “And what did we find? Officers chasing someone tend to run in a particular way, bent low at the knees. It’s sometimes called the ‘Groucho walk’. Our research showed that if you run like this and then try to shoot quickly with both feet on the ground, your arm rises automatically. The officer was trying to do the right thing and was acquitted partly on the basis of our findings.”
Case closed.
