Education Research Police Academy in Apeldoorn makes site available for forensic investigation Written on Wednesday, May 14, 2025 On the grounds of the Netherlands Police Academy in Apeldoorn, a special forensic research project has been launched. Researchers of the shared research group ‘Technologies for Criminal Investigations’ (TCI) (in Dutch) of Saxion University of Applied Sciences and the Police Academy want to test which technologies are most effective for locating buried bodies. The site they use is an enclosed courtyard. ‘This is a unique opportunity’, says senior researcher Louise Lycklema à Nijeholt. ‘We hope it can help locate buried bodies more quickly. And that it will provide new leads in cold case investigations.’ Louise is associated with the shared research group TCI through Saxion University of Applied Sciences. TCI is also part of the Digitalisation and Technology Centre of Knowledge of the Police Academy. The expertise gained from this research can be included immediately in the education provided by the Police Academy. What does the research entail? The researchers aim to find out which technologies are most effective in detecting bodies that are buried in the ground. To do this, they will use six pig cadavers and four different sensors, namely a ground penetration radar (GPR), a gamma ray sensor (GRS), an infrared heat camera and a hyperspectral camera*. What is innovative about this research is that these sensors are mounted on a terrestrial and an aerial robot. This means that the technologies being tested can be applied more quickly and more efficiently to the research. The researchers take frequent measurements both from the air and on the ground, enabling them to study the temperature of the soil and vegetation. The courtyard at the Police Academy is used to recreate a garden, complete with kept plants and a lawn. Previous research into this subject used open terrain, where plants and wildlife could grow and roam freely. In this research, Louise specifically wants to perform tests in an enclosed area. ‘We want to be able to find buried bodies more successfully and more quickly in all types of terrain’, Louise explains. ‘This research will increase our chances greatly. Because we are carrying out this research on the grounds of the Police Academy, we will be able to neatly combine research and practice. It is a unique opportunity that we are now able to do this.’ *Four different ways of measuring The researchers used four types of sensors: Ground Penetrating Radar (GPR): This is a device that can see into the soil without the need for digging. It transmits radio waves into the ground, which are reflected when they encounter obstacles, such as rocks, pipes or bones. This enables you to see what is underground. Gamma Ray Sensor (GRS): This device measures the natural radiation from the ground. All natural materials, such as soil, stones and plants, emit a small amount of radiation. By measuring this radiation, any deviations in the soil can be seen. This can help locate old graves, waste or particular types of soil, for example. Infrared heat camera: A body emanates heat in the beginning of the decomposition process. This camera measures temperature differences in the soil. Hyperspectral camera: This camera can discern many more colours than the human eye can. Where we only see a few colours, this camera sees hundreds. Every material (such as grass, blood or plastic) has its own unique ‘colour signature’. This enables us to see things that would otherwise be invisible to us. The measurements are taken once a week or every two weeks, depending on the decomposition stage of the cadavers. Extraordinary finding ‘One extraordinary finding of our previous research was that nettles started to grow on the graves. It was unclear to us whether the seeds had been carried by the wind or were already in the ground. Or whether perhaps nettles start growing where a cadaver has been buried.’ ‘I am very curious to see what kind of vegetation will grow on the graves, and whether it will include nettles or other plants. That’s why it was important to take soil samples before burying the cadavers –so that we know what is in the ground. The courtyard at the Police Academy is a reasonably isolated space, so plant seeds will not simply be blown there by the wind.' New use of gamma ray sensor ‘The use of a gamma ray sensor (GRS) is new in forensic investigations’, Louise explains. ‘It’s a new type of sensor that measures the natural radiation emitted from the soil. The GRS is currently used extensively in nature development and the measuring of clay and peat layers in the soil. This device measures the soil surrounding the cadaver. It has never been used in forensic investigations.’ ‘The researchers will investigate whether the GRS can also be used for forensic purposes. Can we detect changes in the elements encountered? Cesium-137*, for example, is a radioactive element that is only found in the topsoil. If cesium is found in deeper layers, this could indicate that digging has taken place on that site. It is unclear whether decomposition affects radiation levels. One of the research questions, therefore, is whether gamma ray sensors have a potential forensic use.’ *Cesium-137 Cesium-137 is a radioactive element that does not occur naturally. Currently, it is present everywhere in the environment as a result of the Chernobyl nuclear accident in 1986 and past nuclear testing. Realistic research To make the research as realistic as possible, the researchers used pig cadavers. In terms of skin structure, they are most similar to humans. A total of six cadavers were buried at different depths: thirty, sixty and ninety centimetres. Several empty graves were also created for comparison purposes. Louise emphasises that the pigs were not slaughtered for the research. ‘They came from an educational, organic farm, where a vet euthanised them in a humane way.’ ‘We used pigs that would otherwise have been taken to the slaughterhouse. By law we are not allowed to use cadavers from a slaughterhouse for research. That’s why we bought them directly from a farmer. We also wanted the cadavers to be as intact as possible when we placed them in the graves. Cadavers often do not stay intact if they are slaughtered in a slaughterhouse. For our research, it’s very important that the cadavers are mostly intact, because that is usually also the case with buried bodies.’ Permit and security The Netherlands Food and Consumer Product Safety Authority granted a permit for the research. The area is inaccessible to outsiders and is hidden from view. Researchers use handheld devices and drones to take measurements; any disruption to Police Academy personnel is kept to a minimum. The research will take four years. Louise will publish a progress report each year. After those four years, it is expected that the site can be used for follow-up research with new forensic techniques. This is important because, in some cases, bodies remain buried for years. More information The research results and progress can be found on the Saxion University of Applied Sciences website.