A discussion of current issues and concepts in the practice of skull-photo/craniofacial superimposition

Estimating the Skull‐to‐Camera Distance from Facial Photographs for Craniofacial Superimposition

“…Not surprisingly then, highly varied methods have produced highly varied validation test results —compare, for example, to . Charged debates about the methods' utility have consequently ensued , further fuelled by what (until recently) was only one instance in the literature of an erroneous casework conclusion drawn from a flawed superimposition result —a remarkably good track record across a 80‐year life span, but one nevertheless potentially skewed by strong publication biases. The recent report of 48 misidentifications from a total of 69 identifications made with heavy reliance on craniofacial superimposition methods from the Patio 29 mass grave (representing secret burials of victims from the 1973 coup in Santiago ), raises pressing questions about the superimposition method's reliability and accuracy.…”

Gaudio D, Olivieri L, De Angelis D, Poppa P, Galassi A, Cattaneo C. Reliability of craniofacial superimposition using three‐dimension skull model. J Forensic Sci 2016; 61(1):5–11

“…The report on the reliability of the superimposition method by Gaudio et al (1) followed the method described by Gordon and Steyn (29). Although the use of computers, new "user-friendly" software, and digital images is projected as technical advancements (1,30), the foundational requirements for superimposition method such as visualizing superimposing images in "life size," including the alignment of the auditory meatus in the skull image with the tragus seen in the face image while orientating the skull image and using "wipe" mode in addition to "mix" facility for evaluating the match, are not described by a majority of authors reporting computerassisted superimposition methods (17). Adherence to the above foundational requirements is indicated as safe because the challenges in obtaining anatomically acceptable orientation of a skull image and in visually appraising the relationships between skull and face images that appear at less than "life size" and in "mix" mode will remain the same irrespective of the technical appliance used for obtaining the image overlay such as video device or computer (17).…”

Authors' Response

“…the size and orientation of the skull are changed manually by physically moving the skull, while the image is visualized on the computer monitor, or by moving the digital image on the screen until a good match is found" (12). In Jayaprakash (13) and Gordon and Steyn (14), to which we have made reference, the issue is fully debated.…”