## 2 Methodological Background  
### Forensic Anthropology and Human Identification  
FA addresses the application of physical anthropology (devoted to the study of human body) to legal cases, usually with a focus on the human skeleton. FA methods represent an alternative and counterpart with a much broader range of applicability than other ID approaches (like fingerprints and DNA). According to the Scientific Working Group for Forensic Anthropology (SWGANTH), forensic anthropologists contribute to identification at two levels. The first level is through methods that establish positive identifications. The second level is through methods that contribute to the identification by limiting potential matches to the analyzed individual. Among the former group,  
Figure 1: Papers published using different biomedical image modalities for forensic ID. This figure was obtained by introducing the following queries in Scopus (search performed the 11 th of May 2020): (TITLE-ABS-KEY(forensic identification radiograph) OR (TITLE-ABS-KEY(forensic identification X-ray image))); (TITLE-ABS-KEY(forensic identification CT)); (TITLE-ABS-KEY(forensic identification MRI)); (TITLE-ABS-KEY(forensic identification ultrasound)); and TITLE-ABS-KEY (forensic identification histological image). Those searches provided 771, 398, 68, 49 and 18 papers, respectively. The most commonly employed biomedical image modalities in this domain are X-ray images and computed tomographies (CTs). the SWGANTH includes comparative radiography and the comparison of surgical implants, while it leaves for the second level craniofacial superimposition, biological profiling, medical and/or dental records, abnormalities and pathological conditions, and comparative photography. While surgical implant identification simply involves locating the manufacturer's symbol along with the device's unique serial number, the remaining methods are largely complex to apply. The overall pipeline of SFI is described in Figure 2. Below, we briefly describe the main FA methodologies for human ID that are relevant to this review. The **estimation of the biological profile (BP)** has been studied for more than 300 years, and nowadays it plays a crucial role in narrowing the range of potential matches during the ID process. BP involves the study of skeletal remains with the aim of finding characteristic traits that support determining the identity of the individual. It is a sequential process in which sex, age, stature and ancestry, in this particular order, are estimated. These traits include:  
1. Sex estimation of adult individuals. It is recommended to employ the pelvic and skull morphologic traits [16]. When this is not possible, the discriminant formulas for postcranial skeleton proposed by [17] are recommended. Sex is the first characteristic to be estimated, since many formulas in remaining steps vary depending on sex. 2. Sex estimation of subadults (i.e., children). Sexual characteristics are not fully developed and discriminant until puberty has been passed. For this reason, estimating the sex of children is one of the main difficulties faced by FA when studying subadult individuals. However, there are some approaches that have shown a high potential, like the analysis of morphological features of the ilium, mainly the sciatic notch [18]. 3. Age estimation of dead adult individuals. The analysis of the degenerative processes of the public symphysis is recommended, preferably following the method proposed in [19]. This method should be combined with the analysis of canine root transparency (presented in [20]) according to the two-step procedure proposed in [21]. When this is not possible, the recommended methods are: that proposed in [22] for the analysis of the coxal atrial veneer; that proposed in [23] for the sternal end of the fourth rib; and finally the analysis of the processes of obliteration of the cranial sutures proposed in [24], this being the least reliable method but the only one available on many occasions. 4. Age estimation of dead children.