Crime scene investigation is not unlike what you might have seen on TV. Behind the police tape, the investigators examine the site and identify bodily fluids, such as blood stains, semen or saliva, before carefully collecting samples and preparing them for DNA analysis.
What the detective shows might have missed, however, is the difficulty that comes with processing all the collected evidence. In the Netherlands, all samples need to be sent to one national laboratory in the Hague, the only place in the whole country where forensic evidence can be analyzed.
Getting any information on the collected DNA can therefore take a long time and possibly hinder the investigation, says PhD candidate Michel Nunnenkamp.
Michel Nunnenkamp
PhD research topic: Forensic sampling and downstream analysis at the crime scene
Work: PhD candidate at the Mesoscale-Chemical-Systems group, Faculty of Science and Technology at the University of Twente
Education: Master’s degree in Nanotechnology, University of Twente
Originally from: Germany
‘The samples are processed based on priority, which means that some cases can take weeks to be processed and analyzed,’ he says. ‘And only then do we know if the sample even contained anything usable.’
To save time and help the police solve crimes faster, Nunnenkamp is working on a new rapid test that could be used directly at crime scenes. ‘These tests work very quickly. You can imagine them as a kind of COVID test or a pregnancy test,’ says the UT researcher.
Two tools
Nunnenkamp’s PhD research is part of the project Criminal Investigation DX, which aims to develop two different tools to enhance the efficiency of crime scene investigation.
The first one is a rapid test to determine whether a trace sample contains sufficient DNA that enables suspect identification. This paper-like device, which can immediately determine if the sample contains human DNA, is being developed by scientists in Amsterdam and Wageningen.
At the UT, Nunnenkamp and his colleagues are working on a microfluidic device to establish if the biological traces belong to the same individual.
‘The device we are working on won’t give a full DNA profile, but it will be able to provide basic characteristics related to the person,’ says Nunnenkamp. ‘For example, it can determine if the DNA comes from a male or a female, and it can give us information about their hair color, skin color and eye color. If you have this information, you already know a lot about the suspect or the victim.’
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Evidence collection
The UT scientist is working on a microfluidic chip needed for such a device. On top of fabrication of the chip, Nunnenkamp is searching for an efficient method to collect the evidence and prepare it for further analysis.
‘To use this device, we need to find a new method to collect and extract samples,’ he explains. ‘Nowadays, the police use cotton swabs to collect samples, but this technique doesn’t work for microfluidic chips, because fibers from the swab can block the chip. I’m therefore searching for a way to get the dried liquid, such as blood, into the chip for analysis.’
This requires finding the right material that allows the evidence to be easily collected and then released onto the chip. ‘This is a challenge because in some cases the sample goes too deep into the fibers and cannot be extracted and analyzed,’ says Nunnenkamp. ‘It’s like a stain on your T-shirt. Sometimes you just can’t get it off.’
Police collaboration
To ensure that the resulting device fulfills a real need, the police are directly involved in the research. On their request, the project will not only cover analysis of bodily fluids but also focus on fingerprint DNA analysis, says Nunnenkamp.
‘When a person touches an object, they leave behind oils, and the top layer of the skin sheds a bit,’ he explains. ‘This leaves behind traces of DNA that can be collected and tested.’
Keeping in mind the practical applications of the research, the scientists are careful to develop devices that are easy to use. ‘It should be a simple tool because police officers shouldn’t need to be trained as lab technicians,’ says Nunnenkamp.
Just as importantly, the newly developed techniques need to meet all legal requirements. ‘This part could be easy to forget, but we need to make sure that the evidence is usable in court,’ stresses Nunnenkamp.
Having this vision of a real instrument for real police work is what drives his research forward. ‘I think the project is important because it has a direct impact on the work of the police,’ says Michel Nunnenkamp. ‘Having such a rapid test will save a lot of time for the police and the forensic laboratory.’
