DNA as a Reliable Witness: Can it Solve Crimes?
Imagine a brutal murder with no witnesses. The police have no idea what the perpetrator looks like. But there are traces in the form of DNA – hairs and pieces of skin that do not belong to the victim. Could DNA be the most reliable witness of the future? A witness who does not forget or is affected by the stories of others?
Jan Staaf, an investigator at the serious crime group at the police in Norrköping, believes that grasping at every straw is necessary as the most serious crimes continue to increase. Staaf has used a method via the American company Parabon Labs in four criminal investigations. Their business idea is to produce facial images based on DNA. One successful case is the double murder in Linköping in 2004, where the DNA-generated image pushed the investigation forward, leading to the capture of the murderer.
Forensic geneticist Andreas Tillmar, from the Forensic Medicine Agency in Linköping, explains that while using DNA to solve legal issues is common, producing a picture based solely on DNA is relatively new. Tillmar states that DNA has been used in the Swedish legal system since 2006 to provide clues about appearance and ancestry. However, researchers now seek to take it a step further.
In an ongoing research project, Tillmar, along with Heida Rún Bjarnadóttir, among others, has produced facial images from the DNA of 15 voluntary participants. The images depict skin, hair, and eye color, as well as variables for face shape, freckles, and the probability of being bald and grey-haired. Unlike paternity tests, where exact answers are provided, determining appearance based on DNA is challenging. How we look is influenced by various genes and environmental factors. Communicating this uncertainty is crucial when presenting the findings to law enforcement and other involved parties.
The results from the research project provide probabilities rather than certainty. For example, a text response could state, “The result of the DNA analysis possibly suggests that the unidentified individual has blue eye color and blond hair. Furthermore, the results suggest that the unidentified individual has a biogeographical origin from Europe.” However, when evaluators were tasked with matching the DNA-generated images with actual photos, it was not entirely easy. Some matches were more accurate than others, and one image did not match any of the fifteen participants correctly.
The overall accuracy of the DNA-generated images ranged from 27 to 80 percent. Tillmar acknowledges that there are challenges, including the fact that appearance can change over time. For example, DNA cannot determine if someone has dyed their hair or grown a beard. However, the technology is expected to develop further.
In the programs used by the Swedish Medical Examiner’s Office, facial images can be changed, similar to creating a character in a video game. Skin tone, age, hairstyle, and freckles can all be adjusted. Tillmar himself shares his genetic composition, revealing that his hair color is 30 percent red, 30 percent brown, and 30 percent blond.
While Tillmar does not believe this method will be widely used in the near future, he is convinced that it has the potential to become an important tool in certain investigations. To further validate the method, the researchers plan to proceed with a larger study involving 50 individuals. If the study shows good scientific support, the Swedish Forensic Agency may consider performing the service or outsourcing it to a company specialized in DNA-generated images.