With an identification success rate of about 65 per cent, forensic facial reconstruction uses the small variations in the skull to re-create facial features, writes BETH O'DONOGHUE
THE TROUBLE WITH EARS
About 67 per cent of the facial reconstructions carried out by forensics expert Dr Caroline Wilkinson have less than 2mm of error. The ears, in particular, can be difficult to predict, as can the shape of the mouth.
THE DUBLIN county coroner this week repeated its request for information to help identify a human skull found off Lambay Island, Co Dublin, in 2006. Images of the head of the victim, a white man aged between 25 and 35, created using the skull were also reissued.
Can a skull provide enough information to produce such images? Are these images artistic guidelines or accurate portrayals of peoples’ facial features?
Dr Caroline Wilkinson, an expert in forensic facial reconstruction based at the University of Dundee, was one of a number of forensic experts involved in the original investigation of the Lambay skull. In 2008, using the skull as her template, she produced soft tissue and muscle reconstruction of the person’s head.
Forensic facial reconstruction is just one of a number of forensic methods used in the human identification process. In Ireland the State Pathology Department and the Garda Síochána both employ forensic staff. Additionally, the osteology laboratory at University College Dublin is equipped to allow analysis of human remains. Identifying factors such as age, sex, ethnicity and stature can be determined in the laboratory. This facility has enabled the Forensic Anthropology Study and Research Group at UCD, following the permission of the State Pathology Department, to help the Garda in a number of investigations. However, according to the group’s Dr Rene Gapert, he is not aware of any forensic facial reconstruction experts operating in Ireland.
The theory behind forensic facial reconstruction is that, in the same way we all have unique faces, we all have unique skulls. It is the small variations in the shape, form and proportions of the skull that lead to significant variations in our face, according to Wilkinson, who has carried out up to 50 projects for various police forces, a handful of which were for Irish investigations.
“In general we are approached by the police, and we provide images of the face based on the skull or CT data if a body has been retrieved and has been CT-scanned,” says Wilkinson. “The aim is to be as accurate as possible, but accuracy depends on the amount and condition of the materials given. We have approximately a 65 per cent success rate with our forensic cases.”
Over the past decade Wilkinson has tried to improve the accuracy of facial reconstruction methods by analysing the relationships between the soft and hard tissues of the face, in order to assess old and create new standards for practical use. Technological advances in the past 10 years have also enabled improvements in this area
One of Wilkinson’s highest-profile cases led to the identification of a young girl nicknamed the “Nulde girl” in the press, after Nulde beach in the Netherlands, where the girl’s torso was found in 2001. The child’s head was found days later, farther along the coast, but her facial features had been so badly damaged that she was unrecognisable. Wilkinson was asked to construct an image of the child’s face using the skull. The identification of the child led to the arrest of her mother and stepfather in Italy.
With clear indicators of the worth of forensic facial reconstruction such as this, it can indeed be hoped that the Dublin county coroner’s reissue of these images will be successful.
WHAT TEETH CAN TELL US
The resistance of teeth to environmental damages makes them a good source of uncontaminated DNA for profiling.
A DNA profile is a set of numbers unique to each individual, aiding the identification process.
DID HE HAVE A DOUBLE CHIN?
Developments in clinical imaging have enabled the creation of 3D and 4D images of the muscle and soft-tissue layers. Determining whether a person had a double chin or not is still quite difficult.
WAS HE BALD?
Analysing the skull and other skeletal remains can’t tell us much about variables like hairstyle and eye colour. But advances in imaging technologies have created computer programs that allow a variety of images with these kinds of variables to be produced with ease.
