Freeform Fabrication Assists Forensic Scientists in the Identification of Unknown Victims

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Date

2008-09-10

Authors

Asiabanpour, Bahram
Melbye, Jerry
Melbye, Vicky
Jensen, Evan
Shaw, Joshua

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Abstract

According to the International Homicide Investigators Association, there are currently over 40,000 unidentified bodies being held in coroner‟s and medical examiner‟s offices across the United States. Over half are estimated to be victims of homicide, and all are awaiting positive identification. One technique utilized by forensic anthropologists to establish the identity of unknown skeletal or decomposed individuals is the use of facial reproduction. In facial reproduction, soft tissue approximating muscle and skin is added to the skull in an attempt to reflect how the individual looked during life. Soft tissue depths at specific locations (i.e., certain craniofacial landmarks) are known and have been standardized according to an individual‟s sex, age, ancestry, and body type. For the most part, facial reproduction is still accomplished manually by adding layers of soft clay to represent tissue on the actual skull of the deceased individual. This method is quite time-consuming (often taking two or more weeks) and often not feasible because the skull may be damaged, or the use of clay overlying the actual skull may destroy evidence. To overcome these limitations, researchers have recently turned to Computed Tomography (CT scan) technology to generate CAD files of unidentified skulls, which are then modeled and recreated with rapid prototyping machines. One limitation of this method is that it is dependent on the initial CT scanning instrument, which is not portable and requires that the unidentified remains be removed from their original storage sites (typically morgue coolers or crime scenes) to the location where CT scanning instruments are available (often hospital or clinical settings). Because many of these unidentified remains are either skeletonized or are in various stages of decomposition, the transport of these bodies to locations with CT scanning machines is often not possible or permissible. In this paper, we first propose a new method to rapid prototype skulls via stereolithography (STL) files generated by hand-held portable laser scanners, as opposed to using CT scanning machines. These rapid prototypes can then be fabricated for facial reproduction, negating the use of the actual skull, and not requiring the body be removed from its original location. Also, results of the facial reproduction for an active case are presented. Secondly, we outline preliminary results of a new computerized facial reproduction and superimposition method, which accurately models tissue depth and is not dependent on the manual application of clay.

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