@ Joe M
Firstly, thanks for (some) well-considered, constructive observations.
As a profession, we are well aware of the lack of quality research into bitemarks, most importantly the use of a gold-standard that is acceptable both in terms of diagnostic research and is also forensically relevant, but several studies are currently under way to address this as far as possible.
One current PhD thesis is analysing the prevalence of individual dental features (rotated incisors, etc) within the population as a whole and is producing very useful data, but this is unlikely to yield useable results for another 2 years. Other studies have shown that the biting surfaces of the teeth do appear to produce a pattern unique to an individual, but these are based on analysis of models of teeth rather than bitemarks, and typically have involved smaller sample sizes (<100).
The problem in relating the teeth to the mark lies in the fact that a bite is, by its very nature, dynamic. The teeth and jaws move in the action of biting, the biter and victim move relative to one another (unless the victim is restrained or unconscious), the shape of the bitten tissue alters depending on compression from the bite itself, muscle movement below the skin and the presence of the skeleton relative to the skin surface. These can all produce distortion within the injury, and we are trained to assess this in tandem with the physical evidence and statements provided in order to pick up on any discrepancies. Exclusion is a big part of the process.
As far as research goes, we are unfortunately limited by ethical regulations - it's bloody difficult to gain approval to conduct bite tests just on cadaveric animal tissue, and live-subject research is an absolute no-no!
Even where studies have been conducted on cadaveric tissue, the data cannot necessarily be directly translated to the response of living tissue, as tissue reactions, healing, etc all impact on the appearance over time.
We accept the limitations of the analysis and comparison, and do not examine cases in a frivolous manner. Our duty in such cases is not to convict - it is to provide impartial, unbiased expert opinion to the court (at least, that is how we do it in the UK). I have seen plenty of cases where there is insufficient evidence to even support the allegation of a bite, never mind a comparison with a suspect, and have no qualms about stating such in my reports.
The defence always have the opportunity to call their own expert to assess the case, which helps keep everyone up to date with current research and provides scope for an alternative opinion to be presented.
I take no issue with anyone who wishes to query the methodologies or basis for the work we do, it is welcomed as it maintains an impetus for research and improvement. Suggestions for conducting high-standard research will be welcomed gladly, as few of us are based in academia and thus have little scope to undertake research for ourselves. We are heavily reliant on our research colleagues in that regard.
Biting the hand that feeds IT
