Use of Craniofacial Superimposition in Historic Investigation

A skeleton discovered in Grand Forks, North Dakota was purported to belong to Clelland “Clell” Miller, a James‐Younger gang member, who was killed during the Northfield Bank robbery on September 7, 1876. A 3‐D image from a computer tomography (CT) scan of the skull was obtained, and a craniofacial superimposition was conducted to determine if the skull could belong to Miller. The superimposition method used in this case was to overlay the CT image of the skull onto Miller's postmortem photograph. In addition to the craniofacial superimposition, the images were juxtaposed to compare similarities or differences in facial morphology between the skull and photograph. Superimposition methods can be used to exclude identifications; however, they should not be used as a conclusive method for identification. In this case, there were sufficient similarities between the skull and Miller's photograph; therefore, the skull could not be eliminated as possibly being that of Miller.     

Skull and photographic superimposition: a new approach using a second party's interpupil distance to extrapolate the magnification factor

The photographic superimposition technique requires an antemortem photograph to be enlarged to life size and the skull to be photographed from the same angle as the antemortem photograph. This paper describes how the magnification factor can be extrapolated by measuring the true interpupil distance of a second person and the photographic interpupil distance of the suspect and the second party. A closed-circuit television (CCTV) system is used to determine quickly the skull photographic angle. We believe these techniques are viable and easy to perform.     

Cranio-facial morphanalysis: a new method for enhancing reliability while identifying skulls by photo superimposition

Skull-photograph superimposition continues to be the most prevalent method employed for identifying a skull recovered in a criminal case as that belonging to a putative victim whose face photograph is available. The reliability of identification achieved has been shown to be 91%, indicating the possibility of a skull mismatching with a face photograph belonging to a person other than the actual deceased. This lack of reliability dampens the confidence of the expert and in turn confounds the mind of the judge. It has been shown that the variations in the shape of the facial organs are influenced by the corresponding variations in the skeletal elements of the facial skull. "Cranio-facial morphanalysis", a new anthroposcopic method proposed here for evaluating the shape correlations between a skull and a face photograph, when applied conjointly with skull-photograph superimposition is shown to increase the reliability in forensic skull identification.     

Computer analysis of face and skull size by "quantitative verbal portrait" method

The aim of this study was to develop a "quantitative verbal portrait" method on the basis of universal measured signs of the face and skull. The database includes 90 cases with expert evaluation of photocompatibility with proven identity. Four groups of signs were investigated: DX and DY--the width and height between accurately fixed concrete craniometrical (facial) points and the so-called RX and RY indices--the ratio between distances within the framework of the same direction. The proposed scheme of evaluation helps compare the photograph of a live human and the skull. For evaluating the degree of identity, one should have a summary characterization of all selected signs for the skull and compare it with the sum on the photograph; sometimes it is possible to rule out the identity of the photograph and the skull by the absolute size, e.g., a very large skull cannot belong to a human with a very little face. The score for each group of signs is used for analysis of the information for detecting the similarities. Accumulation and comparative analysis of two information flows are possible: database on portraits of lost subjects and database on graphic images of the skulls of unidentified corpses.     

A method of orientation of skull and camera for use in forensic photographic investigation

The ability to obtain accurate superimposition of the image of the teeth from ante- and post-mortem dentitions is a prerequisite of photographic superimposition. A prototype skull and camera holder is described that enables this to be achieved quickly and simply. The position of the skull relative to the attitude of the face in the photograph can then be documented and hence reproduced as required.     

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

The overlay of a skull and a face image for identification purposes requires similar subject‐to‐camera distances (SCD) to be used at both photographic sessions so that differences in perspective do not compromise the anatomical comparisons. As the facial photograph is the reference standard, it is crucial to determine its SCD first and apply this value to photography of the skull. So far, such a method for estimating the SCD has been elusive (some say impossible), compromising the technical validity of the superimposition procedure. This paper tests the feasibility of using the palpebral fissure length and a well‐established photographic algorithm to accurately estimate the SCD from the facial photograph. Recordings at known SCD across a 1–10 m range (repeated under two test conditions) demonstrate that the newly formulated method works: a mean SCD estimation error of 7% that translates into <1% perspective distortion error between estimated and actual conditions.     

An unusual case of cranial image recognition

We encountered an unusual practical case of craniofacial identification recently. The peculiarity of the case was that the skull itself was not available for examination unlike other such common cases. The supplied material exhibits were, a nearly front view photograph of a skeletonized face and a front view face photograph of the suspected victim. Further, the condition of the skull during taking its photograph was such that its lower and the upper jaws were not in a normal closed condition. The procedure involved in dealing with such a complicated craniofacial identification problem would be quite interesting from a forensic investigator's point of view, since standard methods of skull identification like photo/video superimposition techniques were not at all applicable here. As such, the present case report provides the details of the multiphase procedure adapted by us in dealing with this abnormal case. A solution to this unprecedented craniofacial identification problem was worked out by appropriate exploration of a newly introduced digital image processing technique that is based on craniofacial symmetry perception. The procedure leads to the reconstruction of a superimposable cranial image with upper and lower teeth in normal closed condition for establishment of its identity in usual way.     

Improved skull identification using the superprojection technique with the help of a video-tape system (author's transl)

The photographic identification of a skull through the well-known superprojection technique can be modified and decisively improved by the use of a video-tape system. The identification method based on electronic photo composition is methodically simple to use. It offers the examiner the possibility to recognize the relationship between bone and soft part proportions, and the structure of the bone surface and the details of the soft part shape, as a concrete, tangible characteristic of identity to a substantially greater extent. The large number of controllable characteristics inherent in the ihgh degree of individuality of the skull offers not just an either/or "The skull fits"/ "It does not fit" into a photograph, but achieves proof of disproof of identity.     

Geometric method for determining the skull-portrait aspect in craniofacial identification of the body

Correspondence of the reference graphic images by the aspect is an important condition of craniofacial personality identification. The authors propose methods of determining the skull-portrait aspect by X and Y axes simultaneously. This allows 2 potentialities of comparing the photograph and the skull picture: 1) positioning the skull in a strictly determined aspect estimated by analysis of coordinates of reference points on the photoportrait and 2) positioning the skull and re-estimation of the photoportrait coordinates into the "zero" aspect (zero turning, inclination, and lateral deviation). Hence, all coordinates of the reference points of examined graphic images in the database can be estimated for the zero position and the same scale, which helps automate the search for analogs.     

A new experimental approach to computer-aided face/skull identification in forensic anthropology

The present study introduces a new approach to computer-assisted face/skull matching used for personal identification purposes in forensic anthropology.In this experiment, the authors formulated an algorithm able to identify the face of a person suspected to have disappeared, by comparing the respective person's facial image with the skull radiograph. A total of 14 subjects were selected for the study, from which a facial photograph and skull radiograph were taken and ultimately compiled into a database, saved to the hard drive of a computer. The photographs of the faces and corresponding skull radiographs were then drafted using common photographic software, taking caution not to alter the informational content of the images. Once computer generated, the facial images and menu were displayed on a color monitor. In the first phase, a few anatomic points of each photograph were selected and marked with a cross to facilitate and more accurately match the face with its corresponding skull. In the second phase, the above mentioned cross grid was superimposed on the radiographic image of the skull and brought to scale. In the third phase, the crosses were transferred to the cranial points of the radiograph. In the fourth phase, the algorithm calculated the distance of each transferred cross and the corresponding average. The smaller the mean value, the greater the index of similarity between the face and skull.A total of 196 cross-comparisons were conducted, with positive identification resulting in each case. Hence, the algorithm matched a facial photograph to the correct skull in 100% of the cases.     

Computer-assisted skull identification system using video superimposition

This system consists of two main units, namely a video superimposition system and a computer-assisted skull identification system. The video superimposition system is comprised of the following five parts: a skull-positioning box having a monochrome CCD camera, a photo-stand having a color CCD camera, a video image mixing device, a TV monitor and a videotape recorder. The computer-assisted skull identification system is composed of a host computer including our original application software, a film recorder and a color printer. After the determination of the orientation and size of the skull to those of the facial photograph using the video superimposition system, the skull and facial photograph images are digitized and stored within the computer, and then both digitized images are superimposed on the monitor. For the assessment of anatomical consistency between the digitized skull and face, the distance between the landmarks and the thickness of soft tissue of the anthropometrical points are semi-automatically measured on the monitor. The wipe images facilitates the comparison of positional relationships between the digitized skull and face. The software includes the polynomial functions and Fourier harmonic analysis for evaluating the match of the outline such as the forehead and mandibular line in both the digitized images.     

Computer-aided personality identification by skull and life-time photography by POSKID 1.1 method

An improved method for computer-aided personality identification by the skull, based on the POSKID 1.1 software, consists in investigation of enlarged images of the skull and life-time photograph of the probable individual by coordinates of 49 anatomical points; independent quantitative evaluation of the aspect of each of the compared objects by the X, Y, and Z axes; formal evaluation of the results of comparative study of the skull-portrait by multidimensional discriminant analysis models. The proposed version differs from the POSKID 1.0 software in the method for evaluating the spatial position of the head on the portrait and adequate orientation of the skull in space, which necessitates the utilization of coordinate-regulated holder POSKID 1.1 method is based on multidimensional discriminant analysis and suggests a virtually reliable solution in 76.13-80.65% cases, a probable solution (positive and negative) in 11.61-18.06% cases, and motivated refusal from solution in 5.81-7.74% cases. In case of a probable or indefinite solution further investigations are recommended making use of life-time photographs with different aspects.     

Photogrammetry vs CT Scan: Evaluation of Accuracy of a Low-Cost Three-Dimensional Acquisition Method for Forensic Facial Approximation

Photogrammetry is a three-dimensional acquisition method potentially applicable to the forensic field. This possibility requires the verification of its accuracy. In this study, 3D volumes of skulls are generated to compare the photogrammetry versus the CT scan. In order to provide eligible material to the photogrammetric software, photographs were captured at a distance of 30 cm from the skull placed on a support 1 m in height and illuminated with diffused laboratory ceiling artificial light. A Nikon Coolpix P7100 camera was used. Photographs capture common elements with the previous and the next photograph so as to allow the photogrammetric software to recognize these common points between photographs and create a 3D puzzle. The Zephyr Lite (3DFlow©) software was employed to register the 3D volume. CT-based skulls are taken as a metric reference. The photogrammetry-based skulls are then enlarged according to the measurements of some landmarks or Zygion and Zygion, the distance between end of nasal and base of nasal pyramid for frontal projection, and minimum breadth of the mandibular ramus for the right lateral projection. The accuracy of the photogrammetry is compared to that of the CT scan by measuring the 3D volumes of the skulls studied. Specific landmarks are used as reference points for the measures in both frontal and lateral views. Bland–Altman graph shows homogeneity. The mean difference (1.28 mm) indicates that the measurements taken on the photogrammetry-based skull tend to slightly overestimate compared with the measurements taken on the CT-based skull.     

Skeletal remains of Dr. Eugenio Antonio Berríos Sagredo

It is often noted that even a well-designed osteological technique may not provide accurate results when applied to single forensic cases. Case studies are ideal to test if this concern is valid, and forensic anthropology is a testing ground for applying a population based standard to individual skeletal remains. Secondly, the increasing role anthropologists have played in forensic sciences has aided the medicolegal disciplines in a number of ways. For example, identification of skeletal remains is now more accurate than ever before. Many of these cases have brought perpetrators to court for justice.The purpose of this paper is to use osteological techniques to analyze skeletal remains and make a positive identification. The victim was found partially buried in the sand near El Pinar, Uruguay in 1995. The analysis indicated that the victim was a 45-year old, white, male who was about 170cm tall. Based on preliminary evidence that the victim might be Dr. Eugenio Antonio Berríos Sagredo, a digital superimposition was made using the victim's photograph and the unknown skull. This examination revealed that the skull corresponded consistently with the individual in the photograph. Results were supported by the fact that personal belongings, such as a medal and wrist watch, also pointed to the same individual. Dental records and radiographs when made available later also indicated the same identity. Dr. Berríos was accused of making nerve gas during the dictatorial regime of former Chilean President General Augusto Pinochet. It was also alleged that he made bombs that killed a Spanish diplomat in his laboratory and a Chilean diplomat in Washington, DC. Many complex techniques are often needed to make a positive identification and such was the case for this study. Because of the nature of anthropology as a holistic discipline, such complexity is an integral part of human biology and behavior and can be used successfully in the forensic sciences and medicolegal investigations.     

Remote control skull positioning device for superimposition studies.

The success of the superimposition technique requires positioning the skull in the same posture of the face as seen in the given photograph. A scientific method for positioning the skull has already been proposed by Sekharan. This paper deals with the simple remote control tilt and rotatory device developed in the Forensic Sciences Department, Madras. A pan and tilt arrangement usually utilized in surveillance cameras and two a.c. servomotors, one to tilt the pan and the other to rotate the pan are used.     

Development of equipment for the standardization of skull photographs in personal identifications by photographic superimposition

The technique of photographic superimposition of postmortem specimens (dried skull or head) positioned identically to the orientation in an antemortem smiling photograph is now a recognized method for personal identification of human remains. Previous methods used to produce the postmortem photographs were problematic as orientation of the specimen could not be easily adjusted and positions were not reproducible. The objective of this paper is to describe the design and method of use of purpose-constructed equipment intended to alleviate these problems. The equipment comprises a skull-holding jig based conceptually on the Royal Berkshire Hospital halo frame. This is mounted on a pan-and-tilt device, incorporating calibrated measurement scales, enabling independent movements in each of the Cartesian coordinates. A camera is attached to an adjustable mount running on twin parallel rails allowing the camera-to-specimen distance to be varied. The equipment has proven to be straightforward in use and offers considerable advantages over previously described methods for producing postmortem photographs.     

Skull-photo superimposition and border deaths: identification through exclusion and the failure to exclude

We report on the application of video skull-photo superimposition as an identification method in a case from Ajo, Arizona in which five individuals died after crossing into southern Arizona from Mexico. Initial analyses at the Pima County Forensic Science Center in Tucson, Arizona determined that the disarticulated skeletal remains represented two adult Hispanic males and three adult Hispanic females. Based on biological profiles, both the males and one of the females were tentatively identified and assigned names. The other two females were too similar in age and height, making skeletal separation and identification difficult. As a result, the Michigan State University Forensic Anthropology Laboratory assisted in the identification efforts by performing video skull-photo superimposition on the two unknown females. The skulls were compared to a photograph reported to be one of the missing females. By evaluating facial proportionality and by comparing a number of morphological features of the face and skulls, one skull was excluded as a possible match and one skull was not excluded as a match to the antemortem photo. Because this case was presumed to be a closed disaster, the exclusion of one skull and the failure to exclude the other represented circumstantial identifications.     

Application of Postmortem 3D‐CT Facial Reconstruction for Personal Identification*

Abstract: Postmortem computed tomography (CT) images can show internal findings related to the cause of death, and it can be a useful method for forensic diagnosis. In this study, we scanned a ready‐made box by helical CT on 2‐mm slices in a mobile CT scanner and measured each side of the box to assess whether reconstructed images are useful for superimposition. The mean difference between the actual measurements and the measurements on the three‐dimensional (3D) reconstructed images (3D‐CT images) is 0.9 mm; we regarded it as having no effect on reconstruction for the superimposition method. Furthermore, we could get 3D‐CT images of the skull, which were consistent with the actual skull, indicating that CT images can be applied to superimposition for identification. This study suggested that postmortem CT images can be applied as superimpositions for unidentified cases, and thinner slices or cone beam CT can be a more precise tool.     

An investigation into the accuracy and reliability of skull-photo superimposition in a South African sample

One of the aims of forensic science is to determine the identities of victims of crime. In some cases the investigators may have ideas as to the identities of the victims and in these situations, ante mortem photographs of the victims could be used in order to try and establish identity through skull-photo superimposition. The aim of this study was to evaluate the accuracy of a newly developed digital photographic superimposition technique on a South African sample of cadaver photographs and skulls. Forty facial photographs were selected and for each photo, 10 skulls (including the skull corresponding to the photo) were used for superimposition. The investigator did not know which of the 10 skulls corresponded to the photograph in question. The skulls were scanned 3-dimensionally, using a Cyberware? Model 3030 Colour-3D Scanhead scanner. The photos were also scanned. Superimposition was done in 3D Studio Max and involved a morphological superimposition, whereby a skull is superimposed over the photo and assessed for a morphological match. Superimposition using selected anatomical landmarks was also performed to assess the match. A total of 400 skull-photo superimpositions were carried out using the morphological assessment and another 400 using the anatomical landmarks. In 85% of cases the correct skull was included in the possible matches for a particular photo using morphological assessment. However, in all of these cases, between zero and three other skulls out of 10 possibilities could also match a specific photo. In the landmark based assessment, the correct skull was included in 80% of cases. Once again, however, between one and seven other skulls out of 10 possibilities also matched the photo. This indicates that skull-photo superimposition has limited use in the identification of human skeletal remains, but may be useful as an initial screening tool. Corroborative techniques should also be used in the identification process.