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ePaper created 2015-03-07, 18:13:20 | version 1.33.01
I special _ forensic odontology Confusion can arise from the fact that there is often no unanimous indication regarding which and how many characteristics are neces- sary in order to achieve a positive identification. The recurrence of discordant features excludes identity; the occurrence of several concordant features commonly observed within the popula- tion does not allow a final judgment on identifi- cation, whereas even a few features rarely ob- served can lead to a positive match. An example of this is a case in which the written dental chart describes amalgam restorations in each first molar.Ifthesameisfoundinthedeceased,isthis sufficient evidence to confirm identity? Defi- nitely not, as many people share this restoration pattern. If, however, we also have ante-mortem radiographs of those restorations displaying the exact shape, size and location within each tooth, and these compare favourably with the post- mortem radiographs, then few would argue that a positive match cannot be confirmed. There is, however, still no way to quantify this match, to put a probability ratio or a percentage certainty to it. It may be necessary in some cases to compare all of the teeth in a mouth in order to arrive at a match. In other cases, a single tooth with an un- usual or complex restoration may be sufficient. It has long been the wish of identification ex- perts to be able to quantify such matches, but no reliable method has yet been devised and so a degree of expert subjectivity is still required. Prior to the availability of scientific methods applicable to the issue of positive human identifi- cation, the only real option for relatives and friends to recover the mortal remains of their loved ones was to visually examine them, and make a decision regarding whether the person before them was in- deedwhotheybelievedhimorhertobe.Ontheface of it, positive human identification by visual recog- nition would seem to be a fairly simple matter, as long as the deceased has undamaged facial fea- tures. We can all recognise people who are well known to us by their facial features and manner- isms, even in poor light and at odd angulations. This hasbeenshowntobetrueinmanystudiesconcern- ing the recognition of living people via CCTV secu- rity footage. Why then are there documented cases of misidentification through visual recognition of the deceased, even of intact and undamaged faces? The process of visual recognition is complex and until quite recently not well understood. Clues as to the identity of an individual, either living or de- ceased, rest not only with the physical structure of the face, but also with the variety of facial expres- sions, the display of various mannerisms, and the context in which the individual is seen. A deceased person has lost all facial expression, animation, and context and simply looks different from when he or she was alive. Incipient decompo- sition changes may also be present and go un- recognised. Couple this with the stress and trauma being experienced by the identifier, who may well haveneverseenadeadbodybefore,anditiseasyto seehowsomeonemaymakeamistake.Thisiscom- poundedbythewayvisualidentificationsareoften performed, in that the deceased is presented to the identifier to confirm what the authorities already believe they know. _Identification methods Visual recognition, despite the lack of scientific validityandthepropensityforerror,willforallprac- ticalpurposesremainasamajormethodforpositive human identification. When it is determined that visual recognition is not an option, usually because of trauma, incineration, decomposition, or multiple deaths resulting from a single incident, then foren- sic practitioners are able to rely on more scientific meanstodetermineidentity.Thecommonmethods employedincludemolecularbiology,medicalrecord comparison, fingerprints, and dental record com- parison. DNAprofilesareencryptedsetsofnumbersthat reflect a person’s DNA make-up, which can also be used as the person’s identifier. Although 99.9% of Fig. 3_An example of cranio-facial trauma in a homicide case. Accurate injury description can be vital in these cases. 34 I cone beam1_2015 Fig. 3