Woolridge says it's not the fault of law enforcement. They just aren't educated to recognize bite marks.
"We see a lot of this in child abuse cases," Woolridge says. "We know bite marks are being overlooked."
Bowers, who has reviewed 73 cases in the last five years, says things on the street are not as they are portrayed on popular "CSI" television programs.
"I wish every bite mark I get had been properly processed at the crime scene, autopsy suite or police station, but they aren't," he says. "Incredibly, most cases of suspected bite mark injuries on living or dead persons are not swabbed for possible DNA collection of the biter's trace saliva."
When the proper protocol is followed, bite mark evidence can be of surprising value. David Sweet, DMD, a Canadian odontologist, once reported (J Forensic Sci. 1999 Sep;44(5):1069–72) collecting salivary DNA from a bite mark on a body submerged over five hours in a river, concluding it is advisable that investigators routinely swab for salivary DNA in bite mark cases, even when the amount is thought to be minimal.
There are standards for collecting fingerprints and DNA, and while the American Board of Forensic Odontology has published standards pertaining to collecting bite mark evidence, crime scene investigators are not trained in it, Wright says.
"That's a huge reform that would be beneficial to the field," he says
Faigman advises getting the academic scientific community involved, particularly the National Academies of Science and American Association for the Advancement of Science.
Faigman says currently there are two problems. Most bite mark examiners lack the technical wherewithal to collect research data and do the kinds of statistical analysis necessary, and most academic scientists are not interested in forensic issues.
"The real challenge for people like me who try to bridge the gap between science and the law is to try to come up with ways to get the mainstream scientific community interested in forensic issues," he says.
3D or not 3D
Occasionally, rogue research results in a step forward. Some photographic science, for instance, has emerged that could enhance bite mark analysis, whose future may now lie in the realm of the third dimension.
Traditionally, bite mark photo analysis is carried out in 2D space — 3D information preserved two dimensionally with corresponding distortions. A 2003 paper (Forensic Sci Int. 2003 Aug 12;135(2):115–21) introduced a new 3D documentation, analysis and visualization approach based on a technique called forensic 3D/CAD supported photogrammetry (FPHG) and a 3D surface scanner, which the researchers say is the first 3D approach to bite mark analysis in an actual case.
According to lead author M.J. Thali, Institute of Forensic Medicine, University of Berne, Switzerland, 3D documentation has none of the distortion artifacts that are commonly found with standard 2D photography. All data is documented with a metric 3D measurement, orientation and subsequent analysis in 3D space, providing unprecedented clarity.
The Thali research is an example of the types of results that might be expected when academia embraces law enforcement.
The quality of information and the quality of law enforcement can be enhanced by enlisting mainstream academic scientists, Faigman says.
"Bite mark evidence a decade or two from now might be partly validated and partly invalidated but we might have 50 or 100 percent more information because the research pointed us in directions that we didn't anticipate," he says.
Douglas Page (firstname.lastname@example.org) writes about science, technology, and medicine from Pine Mountain, California.