Evidence evaluation in craniofacial superimposition using likelihood ratios

Craniofacial Superimposition is a forensic identification technique that supports decision-making when skeletal remains are involved. It is based on the analysis of the overlapping of a post-mortem skull with antemortem facial photographs. Despite its importance and wide applicability, the process remains complex and challenging. To address this, computerized methods have been proposed, but subjectivity and qualitative reporting persist in decision-making. This study introduces an evidence evaluation system proposal based on Likelihood Ratios, previously used in other forensic fields, such as DNA, voice, fingerprint, and facial comparison. We present a novel application of this framework to Craniofacial Superimposition. Our work comprises three experiments in which our LR system is trained and tested under distinct conditions concerning facial images: the first utilizes frontal facial photographs; the second employs lateral facial photographs; and the last one integrates both frontal and lateral facial photographs. In the three experiments, the proposed LR system stands out in terms of calibration and discriminating power, providing practitioners with a quantitative tool for evidence evaluation and integration. However, the lack of massive actual data obliged us to focus our study on synthetic data only. Therefore, it should be considered a proof of concept. Nevertheless, the resulting likelihood-ratio system offers objective decision support in Craniofacial Superimposition. Further studies are required to validate in a real scenario the conclusions achieved.R&D project CONFIA (grant PID2021-122916NB-I00), funded by MICIU/AEI/10.13039/ 501100011033 and by ERDF/EU - ‘‘ERDF A way of making Europe’’Grant FORAGE (B-TIC-456-UGR20) funded by Consejería de Universidad, Investigación e Innovación and by ‘‘ERDF A way of making Europe’’Miss Martínez-Moreno is supported by grant PRE2022-102029 funded by MICIU/AEI/10.13039/501100011033 and the FSE+Dr. Valsecchi’s work is supported by Red.es under grant Skeleton-ID2.0 (2021/C005/00141299)Dr. Ibáñez’s work is funded by the Spanish Ministry of Science, Innovation and Universities under grant RYC2020-029454-I and by Xunta de Galicia, Spain by grant ED431F 2022/21Funding for open access charge: Universidad de Granada / CBU

Computer‑aided craniofacial superimposition validation study: the identification of the leaders and participants of the Polish‑Lithuanian January Uprising (1863–1864)

In 2017, a series of human remains corresponding to the executed leaders of the “January Uprising” of 1863–1864 were uncovered at the Upper Castle of Vilnius (Lithuania). During the archeological excavations, 14 inhumation pits with the human remains of 21 individuals were found at the site. The subsequent identification process was carried out, including the analysis and cross-comparison of post-mortem data obtained in situ and in the lab with ante-mortem data obtained from historical archives. In parallel, three anthropologists with diverse backgrounds in craniofacial identification and two students without previous experience attempted to identify 11 of these 21 individuals using the craniofacial superimposition technique. To do this, the five participants had access to 18 3D scanned skulls and 14 photographs of 11 different candidates. The participants faced a cross-comparison problem involving 252 skull-face overlay scenarios. The methodology follows the main agreements of the European project MEPROCS and uses the software Skeleton-ID™. Based on MEPROCS standard, a final decision was provided within a scale, assigning a value in terms of strong, moderate, or limited support to the claim that the skull and the facial image belonged (or not) to the same person for each case. The problem of binary classification, positive/negative, with an identification rate for each participant was revealed. The results obtained in this study make the authors think that both the quality of the materials used and the previous experience of the analyst play a fundamental role when reaching conclusions using the CFS technique.CRUE-CSICSpanish Government Junta de Andalucia CONFIA 2021/C005/00141299 EXAISFI PID2021-122916NB-I00Centro de Investigacion de Galicia "CITIC" - Xunta de Galicia P18-FR-4262European Union (European Regional Development Fund-Galicia 2014-2020 Program)Ministry of Science, ICT & Future Planning, Republic of Korea ED431G 2019/01Universidade da Cor una/CISUG RYC2020-029454-