For years forensics has been an invaluable tool for both small and major crimes alike, uncovering fingerprints, body fluids and hairs. Forensic scientists use their knowledge to approximate the time of death of a victim and give law enforcement a vital timeline that can be invaluable in solving the crime. But now, scientists are able to piece together the identity of a mystery killer.
Sometimes the gruesome realities of a crime can leave the victim’s body unidentifiable and impossible to compare to an index of missing people. Sometimes when perpetrator commits a crime, they’ll leave some sort of evidence at the scene from hair to blood. Scientists collect this DNA and compare it to a database or suspects’ own DNA, and a match will be found if sufficient similarities exist. But what if there is nothing to compare to? What if there is almost no evidence, video footage, or witnesses to a crime but a small amount of DNA? How do you find a criminal with no face…?
Scientists started using a technique called forensic DNA phenotyping to predict the appearance of a criminal from the early 2000s. For years they have been able to determine the sex and race of someone based off of their DNA, but now genes controlling the height and hair, or eye colour of a person can be analysed to help investigators narrow down who they are looking for. Current experiments are focusing on how we can use DNA to predict whether a person has straight or curly hair, skin colour and facial shape.
Although forensic DNA phenotyping’s future looks promising, we have yet to overcome many of the problems associated with it. A prominent issue is that, sometimes, a phenotype is polygenic (more than one gene determines the physical characteristic). Moreover, the environmental conditions can greatly affect observable characteristics, such as how your skin tans in the summer, or how humidity can cause your hair to go curly. Epistasis also presents a challenge for forensic scientists: it can involve one gene ‘masking’ the expression of another, which could lead to unreliable forensics results.
Scientists are working to solve the problems and limitations of Forensic DNA phenotyping, and are optimistic that it will play an important role in the future as it is already being used by police today. Using and improving new techniques, we can identify John/Jane Does and track down a faceless killer to bring them to justice. There may be lots of research to be done into forensic DNA phenotyping, but its future in criminal investigations seems bright and likely to develop further.