A University of Queensland lecturer has developed new methods for bitemark identification.
The new technology was recently used in a Brisbane court case to prosecute a charge of perjury in which the accused had previously been tried for murder but had the verdict quashed on appeal.
The Dentistry School's Dr Alex Forrest said bitemarks on dead or injured people were common, much more so than one might imagine. They were most generally hidden or often went unrecognised, he said.
The reason for their prevalence was that they were commonly associated with both physical and sexual abuse, Dr Forrest said.
The new technology's successful use in Brisbane will have profound implications in Australia, the UK, and in other countries in which bitemark analysis has been problematic.
Dr Forrest said in the recent Brisbane court case, the new digital evidence significantly contributed to a court decision that the defendant was guilty. This case is currently subject to appeal.
Dr Forrest said this had set a legal precedent in Australia to allow the system to have a "second go" at previous cases that had been tried, often without the
benefit of new technologies such as digital imaging or DNA.
Other old cases were now being re-examined as a result, he said.
He said recent figures from Deakin University in 1998 suggested that as many as one in three women and one in five men had suffered some form of sexual abuse, and 33 percent of females and 41 percent of males had suffered some kind of physical abuse.
The new technology also has other applications, notably in tool-mark analysis (marks made by such things as crowbars during break-ins), shoe and foot mark analysis, tyre-mark analysis, and in fingerprint work.
Dr Forrest has succeeded in placing bitemark analysis and evidence on a scientifically sound footing, and has helped remove some of the uncertainty surrounding this
previously contentious area.
The new system not only allowed for the comparison between bitemarks and teeth, but also with simulated wound patterns, and permitted analysis of the dynamic aspects of the biting process, Dr Forrest said.
"The way in which the teeth bite into tissue and the marks left by teeth as they scrape over skin surfaces can be analysed and demonstrated to a court," he said.
"Evidence can be presented visually, using computers and digital projection technology.
"This means tremendous time saving over conventional methods of presenting evidence.
"When one considers that a Supreme Court trial may cost in the vicinity of $20,000 per day, financial savings can be significant.
"It removes the need for complex jargon when the evidence is presented, and allows the jury to make their own judgments about the validity of an expert's claims.
"Bitemark identification is very important because it places someone at the scene of the crime.
"It may not suggest that they committed the murder, but it would suggest they played a role in assailing the victim at a time close to when the major crime was committed."
He said one problem all bitemark experts encountered was the fact that bitemarks were not always complete, and they may be in the form of bruises, indentations, or lacerations.
Dr Forrest examined the flaws of previous methods in order to develop technology to cover these issues.
The new system could also be applied in forensic dental identification, he said.
"In the past, courts have been fairly uncritical in their acceptance of evidence relating to comparison of teeth of a deceased person with dental records," Dr Forrest said.
"However, many young people now have few or no dental fillings, which means
there is no information in the record with which teeth can be compared.
"Far better than using dental records would be a visual identification, something where you could do a direct comparison of the shapes, features, sizes, and details of the teeth.
"Then you would be comparing an entire constellation of minutiae and not just one or two single points."
Those goals have now been achieved with the development of the new method, which allows such things as direct visual comparison of an image of the teeth of a dead person with teeth in a photograph.
"Our biggest achievement has been to formulate a method by which digital evidence of all types can be successfully presented and defended in court," Dr Forrest said.
"We have recognised that, while digital evidence has tremendous potential, it also has a huge potential for misuse.
"Demonstrating that misuse has not occurred depends on our being able to demonstrate the pedigree of the evidence at all stages of the analysis and
presentation, and on being able to repeat those steps if necessary before the court.
"The development of this protocol is most important, because it leads the way for other groups to use this technology."
For more information, contact Dr Alex Forrest (telephone 07 3365 2419, mobile 0407 749 968 or email a.forrest@mailbox.uq.edu.au) or Veronica Toohey
(telephone 07 3346 4713).
