New DNA test identifies perpetrators of sexual violence with minimal evidence
UZ Leuven and KU Leuven have developed a new DNA technique that can identify perpetrators of sexual violence in cases where this was previously impossible. The method, known as SpermFACS, is described as an international first and is now being made available to centres for sexual violence in Belgium and abroad, UZ Leuven announced on Tuesday.
In cases of sexual violence, forensic samples typically contain a mixture of cells from the victim and the perpetrator. Existing techniques attempt to separate sperm cells from vaginal cells in order to build a DNA profile. However, when only a small number of perpetrator cells are present, this often proves impossible, particularly when victims report the incident several days later.
More sensitive technique extends detection window
The new approach offers a solution. Using fluorescence-activated cell sorting (FACS), researchers apply a special fluid that causes only the perpetrator’s sperm cells to light up. These are then passed through a highly precise sorting machine that isolates the luminous cells one by one, yielding a clean DNA profile. According to researchers, the method is five to seven times more sensitive than current techniques and can work even in extreme cases, such as one perpetrator cell among thousands of the victim’s cells.
Crucially, the technology extends the window for obtaining usable DNA. Whereas traditional methods often fail after 48 hours, SpermFACS can generate DNA profiles up to at least five days after sexual contact. This significantly increases the chances of identifying perpetrators, particularly in cases of delayed reporting.
"They are in shock, feel shame or fear, or there are practical barriers"
"The new SpermFACS DNA test increases the likelihood that we can still find reliable DNA evidence even in cases of late reporting,” says Prof. Dr Bram Bekaert, a forensic genetics specialist at UZ Leuven. “In practice, many victims do not report to the police or medical services immediately. They are in shock, feel shame or fear, or there are practical barriers. If the forensic examination then takes place days later, the biological evidence often contains insufficient information. Our new test can make a significant difference for victims, both in the context of judicial prosecution and for their sense of recognition and justice.”
The technique may also prove valuable in complex cases, such as assaults involving multiple perpetrators, where separating distinct DNA profiles is particularly challenging. Because SpermFACS isolates sperm cells with greater precision, it becomes easier to distinguish between different individuals.
The method has not been patented, allowing laboratories worldwide to adopt it. Researchers are already working on further developments, including miniaturising the technology onto microchips to enable faster and more cost-effective analysis. In the longer term, they hope to apply the technique to other types of forensic evidence, such as DNA traces found on clothing or objects.
#FlandersNewsService | © PHOTO IMAGEBROKER
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