The Utility of Skeletal and Surgical Features for the Personal Identification Process: A Pilot Study

Towards an integrative approach to the biological profile

One of the most important tasks in forensic anthropology is the construction of the biological profile, classically defined as a set of four basic biological descriptors: biological sex, age-at-death, ancestry, and stature. Yet, our empirical and technological abilities in reconstructing the life experiences and health from skeletal remains far exceed these four parameters and forensic anthropology could benefit from further descriptors in the search for an identity. In this paper, we propose the inclusion of two other investigations to forensic anthropology practice to implement the already known biological profile: the interpretation of bone disease and lesions, and forensic toxicology on unconventional biological matrices. These analyses can provide information regarding health, habits, and disease burden, and by implementing them in our practice of forensic anthropology, they have the potential to improve the biological profile. We also propose a new term that can include not only the classical biological profile but also further descriptors, namely, the "biocultural profile".

The potential of facial nevi in personal identification

Forensic anthropologists dealing with personal identification (PI) of human remains have recently stressed the need to explore the potential of "secondary identifiers" for identifying victims who died in particular events for whom images often represent the main antemortem data available. Being the face the part most exposed in images, characteristics as pigmented skin lesions (PSLs), can be crucial if combined with other input. Since no data is available on frequencies and distribution of facial PSLs in the general population, this study aims at systematically collecting such data to verify their potential in PI and to open a debate on the aid that "secondary identifiers", regardless of their specific nature, can give to the identification of the deceased in specific forensic contexts. A retrospective analysis on three-dimensional facial models of 1039 Italian subjects (from 4 to 84 years old) was conducted to examine the incidence of PSLs discriminated according to size and position in well-defined facial areas. From the collected data we developed a probabilistic approach providing the likelihood ratio (LR) for two settings: (1) the relative frequencies of nevi in the various facial areas, providing the deriving compound probability of owning a certain facial PSLs pattern; and (2) codes describing the facial nevi pattern of each individual of our population, thus testing their uniqueness and so their potential in PI. The calculated LRs mostly proved high identifying strength, particularly when provided by the compound probability-based approach. Data on incidence and position of facial nevi, their generated codes, and the probabilistic approach here presented, all constitute a starting point for advancing secondary identifiers. Nonetheless, although this preliminary study proved facial PSLs as valuable and potentially useful for identification, their significance and validity should be interpreted with caution as we are still at the first theoretical step clearly based on ideal conditions, and thus further investigations are due on the limitations of their use in practical identifying settings. Therefore, being this systematic study only a preliminary one in its nature, it is recommended not to use this kind of approach until further studies will test its validity in several practical conditions.

All that glitters is not gold: X-ray fluorescence analysis of a fixed dental prosthesis from Colecção de Esqueletos Identificados Século XXI, Portugal (CEI/XXI)

Access to better health care anticipates that more medical devices can be found alongside skeletal remains. Those employed in oral rehabilitation, with available brands or batch/series, can prove useful in the identification process. A previous study in the Colecção de Esqueletos Identificados Século XXI described macroscopically the dental prostheses. An unusual case of a dental device with chromatic alterations demonstrated to require a more detailed analysis. The individual, a 53-year-old male, exhibited, at both arches, a fixed tooth-supported rehabilitation, with gold colouring classified initially as a gold-palladium alloy. Simultaneously, a green pigmentation deposit was observable in bone and prosthesis. This investigation aimed to verify the elemental composition of the dental prosthesis alloy. Elemental analysis was performed by X-ray fluorescence in two regions (labial surface of the prosthetic crown and the root surface of the lower right lateral incisor). Both the spectra and the qualitative results found higher levels of copper and aluminium, followed by nickel, iron, zinc, and manganese. No gold or palladium was detected. The most probable assumption is that a copper-aluminium alloy was used, as its elemental concentration corresponds to those measured in similar devices. Dental prostheses of copper-aluminium alloys have been made popular since the 1980s, particularly in the USA, Japan, and Eastern Europe. Apart from the biographical information, it was also known that the individual's place of birth was an Eastern European country, which highlighted the usefulness of this type of information when dealing with missing people cases.

Rumor has it: A narrative review on the use of skeletal non-metric traits and variants for personal identification

The human skeleton displays an immense array of traits and variant features that are elements of inter-individual variability. The general assumption is that they may represent individualizing markers for the personal identification of unidentified decedents, but very few works consider them as such. This review provides an overview on the possible use of non-metric traits and skeletal variants for personal identification. The paper discusses the issues related to unquantified comparisons, then it presents a statistical approach based on frequencies of these features for identifying unknown remains. Narrowing down an initial number of 1000 papers, the core of the review is represented by 10 papers that considered non-metric traits and skeletal variants as individualizing features, according to both qualitative and quantitative assessments. Despite visual examination remains the gold-standard, more sound methods are requested to quantify the strength of a match or a mismatch. This especially applies in the wake of juridical demands, hence also satisfying the desire of prosecutors and judges to rely on a "quantified" risk. To this purpose, non-metric traits and skeletal variants seem to be a suitable tool to provide quantified evidence, when related frequencies are known.

Re-examining so-called 'secondary identifiers' in Disaster Victim Identification (DVI): Why and how are they used?

Disaster victim identification (DVI) refers to the identification of multiple deceased persons following an event that has a catastrophic effect on human lives and living conditions. Identification methods in DVI are typically described as either being primary, which include nuclear genetic markers (DNA), dental radiograph comparisons, and fingerprint comparisons, or secondary, which are all other identifiers and are ordinarily considered insufficient as a sole means of identification. The aim of this paper is to review the concept and definition of so-called 'secondary identifiers" and draw on personal experiences to provide practical recommendations for improved consideration and use. Initially, the concept of secondary identifiers is defined and examples of publications where such identifiers have been used in human rights violation cases and humanitarian emergencies are reviewed. While typically not investigated under a strict DVI framework, the review highlights the idea that non-primary identifiers have proven useful on their own for identifying individuals killed as a result of political, religious, and/or ethnic violence. The use of non-primary identifiers in DVI operations in the published literature is then reviewed. Because there is a plethora of different ways in which secondary identifiers are referenced it was not possible to identify useful search terms. Consequently, a broad literature search (rather than a systematic review) was undertaken. The reviews highlight the potential value of so-called secondary identifiers but more importantly show the need to scrutinise the implied inferior value of non-primary methods which is suggested by the terms "primary" and "secondary". The investigative and evaluative phases of the identification process are examined, and the concept of "uniqueness" is critiqued. The authors suggest that non-primary identifiers may play an important role in providing leads to formulating an identification hypothesis and, using the Bayesian approach of evidence interpretation, may assist in establishing the value of the evidence in guiding the identification effort. A summary of contributions non-primary identifiers may make to DVI efforts is provided. In conclusion, the authors argue that all lines of evidence should be considered because the value of an identifier will depend on the context and the victim population. A series of recommendations are provided for consideration for the use of non-primary identifiers in DVI scenarios.

The dental prosthesis (removable and fixed) from the Colecção de Esqueletos Identificados Século XXI (CEI/XXI)

For identification of the unknown, the analysis of individualizing characteristics is a paramount procedure, which allows the reconciliation of antemortem with postmortem data. Worldwide, populations are commonly affected by tooth loss, leading to procedures of oral rehabilitation, such as dental prostheses. Although the potential of these devices for human identification is well known, the lack of marks or serial numbers as well as scarce systematic register on databases may difficult its use. The objective of this paper is to present and describe the cases with dentures and bridges of an identified osteological collection, the Colecção de Esqueletos Identificados Século XXI. All the individuals were macroscopically observed, and the cases presenting dental prostheses were registered. A total of thirty-one individuals (20 females; 11 males), ages 38 to 91 years, presented 49 dental prosthesis (removable or fixed), of various materials. The removable acrylic dentures (n = 42) were the most frequent. No identifying marks or production labels were found. This research reinforces two focal points: the value of studying and recognizing medical devices and their application for identification, and the relevance of identified skeletal collections for the advance of forensic science in the current multidisciplinary approach.

Exploring the potential of cranial non-metric traits as a tool for personal identification: the never-ending dilemma

Forensic anthropologists tasked with identification of skeletal remains often have to set up new strategies to overcome the limitations of conventional individualizing markers. A sound acquaintance with non-metric traits is essential for a reliable distinction between normal variations and pathological or traumatic conditions, yet the role of cranial variants in the identification process is still somehow ill-defined. One hundred crania (50 males and 50 females) of known sex and age were selected from the Collezione Antropologica LABANOF (a documented contemporary skeletal collection) and non-metric traits were scored as present or absent and by side. The frequencies of 13 traits were used to calculate the compound probabilities to find an individual with an exact combination of cranial features in the worldwide population. The probabilities of the majority of the individuals (53%) are within the 1 out of 10 million-1 out of 1 million interval. However, a fair number of subjects (25%) of the sample have the probabilities falling into the 1 out of 1 billion-1 out of 100 million interval, while the probabilities of a small portion of the sample (10%) are less than 1 out of 1 billion. This pilot study illustrates that some combinations of cranial variants are quite rare and may represent potential evidence to discern presumptive identifications, when an appropriate set of traits is selected and antemortem data are available for comparison. However, further research on larger and various samples is needed to confirm or discard the use of combinations of cranial non-metric traits as individualizing markers.

New data about the 21st Century Identified Skeletal Collection (University of Coimbra, Portugal)

After the publication of the first article in 2014, 21st Century Identified Skeletal Collection, housed in the Laboratory of Forensic Anthropology, Department of Life Sciences at the University of Coimbra, Portugal, has been growing. Currently, the collection is composed of 302 complete adult skeletons of both sexes, which means that in 5 years it has doubled. The collection consists mostly of elderly individuals, with only 12.25% of the individuals aged less than 61 years old. All individuals are Portuguese nationals who died between 1982 and 2012. Ninety individuals exhibit prostheses, other medical devices and signs of surgical procedures. Moreover, a sub-collection of experimentally burned skeletons is under development, and currently includes 56 individuals (18.54% of the collection). The 21st Century Identified Skeletal Collection constitutes a fundamental tool for forensic anthropology research, including the development and validation studies of methods that focus on elderly individuals, as can be ascertained by the numerous scientific publications and academic scholarship that have been produced in previous years.