Belgian bioscientist Sofie Claerhout has been gaining fame abroad for years by using the DNA of family members to track down murderers in unsolved crimes. Thanks to a change in the law, she will soon finally be able to help solve Belgian cold cases in the same way.
Federal Justice Minister Vincent Van Quickenborne is currently working on a draft law that stipulates that the Belgian court will soon be able to trace relatives of the perpetrator via DNA research – a law is coming into being largely due to the pioneering work of Claerhout.
Since 2015, the Doctor of Forensic Genetics at KU Leuven has been researching the male Y chromosome. With ‘Perpetrator Unknown’, her recently released book, she wants to convince the remaining sceptics that the Y chromosome can be the key to unlocking numerous unsolved murder cases. The first cold case she hopes to solve in Belgium is that of Ingrid Caeckaert.
Dozens of cold cases
On March 16, 1991, 26-year-old Ingrid Caeckaert was brutally stabbed to death in the elevator of her apartment block in the coastal municipality of Knokke-Heist. Despite thousands of witness interviews, the case has never been solved. Today, over thirty years later, Caeckaert's parents still do not know who killed their daughter, and why. Like this case, there are dozens of cold cases in Belgium.
"In the Caeckaert case, the DNA has so far not yielded a breakthrough, because according to Belgian law, a DNA trace may only be compared with that of the suspects or people who were previously convicted in our country,” Sofie Claerhout told De Morgen. “But we could also use that DNA trace to find relatives of the perpetrator, even distant ones, and that's where the Y chromosome comes in handy.”
"The Y chromosome is a sex chromosome,” she added. “It is also called 'the genetic wasteland': it contains very little information about your genes or your appearance. It only determines whether you are biologically male and what paternal line you follow. But what is so useful about the Y chromosome is that it is transmitted from father to son almost unchanged."
Tracing the family tree
While second cousins share only 12.5% of their DNA, 95% of their Y chromosome is identical. This means that by looking at the Y chromosome, you do not even have to find the closest family member of the perpetrator; the DNA of a distant second cousin can be enough.
"This can be done by making an appeal to a hundred men from the neighbourhood to give their DNA. After that, researchers like me can get to work with the Y chromosome. If we find a similar Y chromosome in those DNA samples as that of the crime scene, we focus on that."
By looking at the small differences between the chromosomes, scientists can then determine whether it concerns a close relative like a brother, or a distant family member. "We combine this with family tree research, which allows us to exclude branches of the family that have moved to other cities, for example. That way you can get to the perpetrator within a few months, without him having given DNA himself."
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Van Quickenborne's bill stipulates that in an unsolved murder case, volunteers can be recruited to deliver DNA. After the examination, their DNA would be destroyed again. The change in the law could not only provide closure for Ingrid Caeckaert’s parents and many others, but also for Sofie Claerhout.
"When I read about Ingrid Caeckaert, I realised for the first time that our research can make a difference in solving such murder cases,” she said. “I also felt personally connected to Ingrid. We both have West Flemish roots. At the time I heard about her case, I was 26, the same age as she was. In the meantime, I have met the parents several times. It's high time we got to work on this case."
