Personal Identification of Deceased Persons: An Overview of the Current Methods Based on Physical Appearance

Post-mortem to ante-mortem facial image comparison for deceased migrant identification

The identification of deceased migrants is a global challenge that is exacerbated by migration distance, post-mortem conditions, access to ante-mortem data for comparison, inconsistent international procedures and lack of communication between arrival and origin countries. Due to low technology requirements, fast speed analysis and ease of transferring digital data, facial image comparison is particularly beneficial in those contexts, especially in challenging scenarios when this may be the only initial ante-mortem data available to identify the deceased. The Facial Identification Scientific Working Group (FISWG) professional guidelines for facial image comparison were developed for living facial appearance, and, therefore, a tailored protocol for the application of post-mortem to ante-mortem facial image comparison was proposed and evaluated in this research. The protocol was investigated via an inter-observer and an accuracy study, using 29 forensic cases (2001-2020) from the University of Milan, provided by the Laboratory of Forensic Anthropology and Odontology. In order to replicate a migrant identification scenario, each post-mortem subject was compared to all 29 ante-mortem targets (841 comparisons). The protocol guided the practitioner through stages of facial image comparison, from broad (phase 1) to more detailed (phase 3), eventually leading to a decision of 'exclusion' or 'potential match' for each post-mortem to ante-mortem case (phase 4). In phase 4, a support scale was also utilised to indicate the level of confidence in a potential match. Each post-mortem subject could be recorded with multiple potential matches. The protocol proved to be useful guide for facial image comparison, especially for less experienced practitioners and the inter-observer study suggested good reproducibility. The majority (82-96%) of ante-mortem subjects were excluded at the first stage of the protocol, and 71 full post-mortem to ante-mortem facial image comparisons were carried out. On average, two or three potential matches were recorded for each post-mortem subject. The overall accuracy rate was 85%, with the majority (79%) of ante-mortem non-targets correctly excluded from the identification process. An increased number and quality of available ante-mortem images produced more successful matches with higher levels of support. All potential matches involving non-targets received low levels of support, and for 73% of the post-mortem subjects, the ante-mortem target was the only recorded potential match. However, two ante-mortem targets were incorrectly excluded (one at the first stage of the protocol) and therefore changes to the protocol were implemented to mitigate these errors. A full protocol and a practical recording chart for practitioner use is included with this paper.

Who are they? A retrospective study of unidentified bodies in Institute of Medical-Legal Paris from 2018 to 2023

"I still don't realize that he's dead.... I cried over it. It makes me sad to know that he was buried unaccompanied on his last trip. We were all shocked." This testimony corresponds to a family whose relative was buried in an anonymous grave 6 months after his disappearance was reported to the police. It is estimated that between 1 000 and 3 000 unidentified bodies are buried in anonymous graves in France each year. Most of these decedents have passed through the medico-legal system. However the identification of these bodies, outside the context of mass disasters, remains a complex problem. Several national and international publications have highlighted the prevalent problem of unidentified burials and the consequences for families who do not know the fate of their loved ones, specifically, whether they are alive or deceased. This 6-year retrospective study (2018-2023), covering a total of 2 324 unidentified decedents admitted to the Institute of Medical-Legal Paris (IMLP), aimed to assess the impact of the identification protocol implemented in 2017 on the number of bodies that remain unidentified (n = 164). In addition, this study aimed to establish profiles for individuals who remained unidentified with the objective of identifying the factors that hinder their identification and developing correlated methods to address these issues. The results of this study were compared with other published studies to highlight the global problem and the ongoing need for collaboration between forensic practitioners and relevant authorities.

Key points

Despite great advances in human identification, unidentified decedents remain a global problem.This 6-year overview study covering a total of 2 324 unidentified bodies admitted to the IMLP provided relevant information about the unidentified decedent population and assessed the impact of a protocol established in 2017 on the rate of deceased buried without identity in Paris.The need to establish a national database in France to properly document and disseminate information on missing persons and to centralize the biological profile of unidentified bodies is key, as without antemortem information or a biometric database there can be no matching.

Orofacial assessment as digital path for forensic and legal evidence record

In forensic scenarios, such as armed conflicts or mass disasters, the oral cavity can be a valuable source of identification information relevant to legal issues. In many European Union countries, it is mandatory to register dental records for identification purposes. A pilot and quasi-experimental study was performed. The study aims to analyze two methodologies, photography and wireless intraoral (IO) laser scanner, in the scope of the orofacial record in forensic pathology, highlighting their impact on human identification. The IO scanner i700 (Medit, Lusobionic, Portugal) and Canon 5D-Full Frame equipment were used to record the individual status, living patients (n = 5), and forensic cases (n = 5). IO and extraoral anatomical structures were recorded following six parameters: time, mineralized and soft detail, communication, extra devices, and distortion. The statistical analysis was performed in accordance with a scoring system and Mann-Whitney (P < 0.05) analysis. The photography method recorded extraoral data for all samples (score range between 15 and 23). The time elapsed to complete an IO scan in forensic cases was shorter than with photography, without requiring additional sources of light or mirror devices. Living patients and corpses identified statistically significant differences. It can be concluded that laser scanners are a valuable tool in the field of forensic pathology and can be used to record and analyze anatomic-morphological data for identification purposes accurately.

Key points

Human identification engages in orofacial details records.Photographic and laser scans record intraoral and extraoral anatomic structures.Forensic cases assessed by intraoral scanner technology are accurate and less time-consuming, optimizing the orofacial data for identification.

Digital intraoral and radiologic records in forensic identification: Match with disruptive technology

While clinical dentistry has seamlessly integrated the digital revolution, there is a gap in the technological capabilities of forensic dentistry.The study aimed to compare the superimposition accuracy of two different three-dimensional record formats, namely the intraoral scanner and cone beam computer tomography, in the context of forensic identification.The sample consisted of randomly selected adults (n=10) of both sexes aged between 20 and 50 years. Following the acquisition of data using the Medit i700 wireless scanner and the iCAT Tomograph with InVivo software, the records were analysed and compared through superimposition using Medit Scan Clinic software to assess the technical precision of anatomical identification details.The results obtained through the superimposition of dental and bone records following intra- and inter-observer analysis enabled an accurate comparison and identification of an individual. This method can differentiate between positive and negative matches, achieving exclusion results and offering a potential solution to overcoming the absence of a standardisation procedure in human identification.

Facial recognition for disaster victim identification

Mass disaster events can result in high levels of casualties that need to be identified. Whilst disaster victim identification (DVI) relies on primary identifiers of DNA, fingerprints, and dental, these require ante-mortem data that may not exist or be easily obtainable. Facial recognition technology may be able to assist. Automated facial recognition has advanced considerably and access to ante-mortem facial images are readily available. Facial recognition could therefore be used to expedite the DVI process by narrowing down leads before primary identifiers are made available. This research explores the feasibility of using automated facial recognition technology to support DVI. We evaluated the performance of a commercial-off-the-self facial recognition algorithm on post-mortem images (representing images taken after a mass disaster) against ante-mortem images (representing a database that may exist within agencies who hold face databases for identity documents (such as passports or driver's licenses). We explored facial recognition performance for different operational scenarios, with different levels of face image quality, and by cause of death. Our research is the largest facial recognition evaluation of post-mortem and ante-mortem images to date. We demonstrated that facial recognition technology would be valuable for DVI and that the performance varies by image quality and cause of death. We provide recommendations for future research.

Metric evaluation of the anterior nasal spine to estimate sex and population group in South African individuals

INTRODUCTION

The anterior nasal spine is a pointed, midline projection of the maxilla. This bony structure dictates the overlying soft tissues providing the phenotypic features of the nose and upper lip and determines the differences in the mid-face morphology. Little data is available on the metric features of the Anterior nasal spine (ANS). This study aimed to perform metric evaluations of the ANS of white and black South African males and females to ascertain if morphological variations exist and if the differences are viable for the use in sex and population identification.

MATERIALS AND METHODS

The sample included 100 CBCT images for each population and sex group. Linear and angular measurements of the ANS were recorded in both the sagittal and axial planes.

RESULTS

Classification decision trees (pruned) were fitted to ascertain the relationship between population group, sex and the ANS measurements including and excluding age. For population group, all the ANS measurements were statistically significant for females but in males, all the ANS measurements were significant when performed individually. However, when fitted to the classification tree, Sagittal 2 did not show any statistical significance. When considering sex, only 2 of the ANS measurements (Sagittal 2 and Axial 1) were found to be significant. The results did not differ significantly when comparing the decision trees including and excluding age.

CONCLUSIONS

White South African individuals presented with a longer ANS that produced a more acute angle whereas black South African individuals presented with a shorter ANS and a more obtuse angle. Additionally, males presented with a longer ANS compared to females. ANS measurements were found to be more relevant for population discernment than for sex.

Possible uses of Hunter-Schreger bands of dental enamel for automated personal identification

BACKGROUND

Hunter-Schreger bands (HSB) are optical phenomena observed on tooth surfaces under polarized light, resulting from the intersection of enamel prisms. Anthropological studies demonstrate the prevalence of HSB in large mammals, contributing to enamel resistance. Historically, John Hunter and Schreger depicted HSB in dental literature. In dentistry, HSB play a role in non-carious cervical lesions (NCCL) and internal dental perikymata, suggesting their potential for personal identification. Personal identification, crucial in both daily and professional life, involves biometric characteristics, such as fingerprints or facial recognition. The need for non-invasive, rapid, and user-friendly methods has prompted the exploration of using HSB dental images for personal identification. The review aimed to consolidate studies employing HSB for personal identification.

METHODS

The scoping review was carried out strictly following the PRISMA-ScR checklist; the search was carried out on tree databases (PubMed, Scopus, Science Direct,) and a register (Cochrane library).

RESULTS

The research produced a number of bibliographic sources totaling 410. With the removal of duplicates, 334 were obtained; potentially eligible articles amounted to 14, of which only 4 fully complied with the criteria of eligibility.

CONCLUSIONS

From the data in the literature, we can assert that HSB could be used in personal identification, as they are characteristics that are difficult to change and easily detectable.

Identification issues in bodies maimed by train fatalities: The role of the forensic pathologist

Traffic accident injuries are relevant causes of mortality in industrialized countries. Among traffic accidents, the most destructive effect on the victim's body is produced by trains, which in a very short time provoke a complete distortion of the normal anatomical profiles and extensive amputations of the body. Deaths by severe body mutilation and/or decapitation require complex forensic investigation, as the victims' identification and the recognition of their body are not often feasible. In this study, a retrospective analysis of a series of cases of railway accidents is presented, with the aim of showing potential identification strategies, including a systematic physical re-assembling of the body. Among the railway fatalities assessed at the University Institute of Legal Medicine of Milan from 2016 until 2020, 61 cases were analyzed, focusing on the collection of postmortem data to improve accuracy for the identification of the victims. The results showed that the identification could be based on elements traditionally called "secondary identifiers" which, however, are becoming more and more important for positive identification, especially when dealing with migrants, vagrants, and homeless people. However, several issues need to be considered such as the limitations of the public prosecutors to perform expensive analyses (i.e., genetic testing), and the lack of antemortem data to be compared with postmortem findings, both odontological and fingerprint. In cases where it is not possible to proceed with identification or formal recognition of victims of railroad accidents with severe mutilations, a systematic physical re-assembling of the body is critical to reaching positive identification.

Potential of plant DNA information in determining the provenance and identify of unknown victims

Determination of the personal identity of victims is particularly important for the settlement of criminal cases. Unfortunately, useful information for identification is not always available. We here propose that the particles (pollens) of some plants with specific geographical distributions extracted from human lung tissues contribute to further determining the provenance or long-term residence of unknown victims, thereby considerably narrowing the search scope of the victims. We collected lung tissues from 155 victims with diverse causes of death, extracted DNA from lung tissues, sequenced the DNA fragments of plants on the Illumina Hiseq platform, and barcoded the plant species using phylogenetic methods. Finally, 108 unique plant sequences were detected in 55 samples and identified to belong to 36 species in 32 genera of 29 families. These plants were predominantly insect-pollinated crops and ornamental plants. No significant difference was observed between male and female samples, between urban and rural samples, or among samples of different ages and different sample sizes. There were 16 samples with 21 wild plant species. The original sources of 15 samples were overlapped with the distribution regions of detected plants; 2 samples narrowed the original sources to 2 provinces, which were quite coincident with their source places; 1 sample had no overlapping with its victim source region. Although plant information was only found in one-third of the samples, we further demonstrated the great potential of plant eDNA in identifying the source of unnamed corpses in a real-world case. We used plant eDNA from lung tissues to explore the provenance of an unknown female corpse found in Beijing. The source place of this victim was narrowed to Guangdong and Guangxi provinces, and finally, we confirmed her true identity in the list of missing persons in Guangxi Province. In the presence of a well-covered local reference library, the plant species detected in the lungs can be accurately identified. In difficult criminal cases where physical evidence is relatively weak, plant DNA information may provide new clues. In conclusion, the plant particles trapped in the lungs are promising to help forensic experts narrow the search scope for the identity of unknown victims.

A guide to classify tattoo motives in Mexico as a tool to identify unknown bodies

Justification

In Mexico, the number of unidentified bodies has been steadily rising for years. By now, more than 50,000 bodies are considered unidentified. Forensic laboratories that could perform comparative molecular genetic investigation are often overburdened and examinations can take months. Therefore, pragmatic approaches that can help to identify more unknown bodies must be sought. The increased use of distinctive physical features might be one, and the high rate of tattooed people in Mexico points towards a great potential of tattoos as a tool for identification. The prerequisite for a comparison of antemortem (missing persons) and postmortem (unknown bodies) data is an objective description of the particularities, e.g., of the tattoos. The aim of this study was to establish an objective classification for tattoo motives, taking into consideration local preferences.

Methods

In the database of the medicolegal services of the Instituto Jaliscience de Ciencias Forenses (IJCF) in Guadalajara, postmortem data of 1000 tattooed bodies from 2019 were evaluated. According to sex and age, the tattooed body localization and the tattoo motives were categorized.

Results

The 1000 tattooed deceased showed tattoos on 2342 body localizations. The motives were grouped and linked to the following 11 keywords (with decreasing frequency): letters/numbers, human, symbol (other), plant, symbol (religious), animal, object, fantasy/demon/comic, tribal/ornament/geometry, other, unrecognizable.

Conclusion

Using the proposed classification, tattoo motives can be described objectively and classified in a practical way. If used for antemortem (missing persons) and postmortem (unknown bodies) documentation, motives can be searched and compared efficiently—helping to identify unknown bodies.

Rediscovering the value of images in supporting personal identification of missing migrants

The crisis concerning the identification of dead migrants is forcing forensic scientists to deal with the unavailability of classical antemortem (AM) data such as radiological information and DNA. However many times there is abundant AM photographic data of which the availability and quality is underestimated. Independently of when facial image comparison can be used as a valid identification method, description of the unexpected quality and quantity of images in the scenario of unidentified migrant decedents is given in this observational study. It focuses on the overall characteristics of the AM images available for a group of 74 missing migrants related to the disaster of October 3rd, 2013. 394 images were collected: an average of 6 for each missing person. 18% are original pictures, 47.5% scans of original images, 9.9% scans of printed images while 9.4% downloaded from social networks such as Facebook. 42.7% of images resulted in focus. Among all the images, about the 10% has been used in the personal identification process to ascertain the identity of 22 persons, because of the visibility of identifying details (facial, dental and body features). The importance of such a finding should not be diminished by its simplicity. Today, those involved in collecting AM information from relatives of dead migrants are underestimating the possible presence of images, even in sub-Saharan populations, where, contrary to belief and data, technology, though simple, is available and images may turn out to be abundant and useful (and at times the only resort) for identification.

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.

Explosion-related deaths: An overview on forensic evaluation and implications

Purpose

Explosion-related deaths are uncommon events which require expertise and confidence so that an appropriate death investigation can be performed. The present study aims to provide a detailed forensic analysis of the issues and implications arising in the event of an explosion.

Methods

A retrospective review of casualty data was conducted on electronic literature databases. Cases concerning deadly explosions registered at the Milan Institute of Legal Medicine were examined and analyzed altogether.

Results

Explosions may involve closed or open systems. A security assessment of the site is always necessary. Alterations of the site due to rescue procedures can occur; thus, on-site forensic investigation should be adapted to the environment. Then, a study protocol based on autopsy procedures is presented. Application of the postmortem radiology enforces forensic procedures both for the analysis of blast injuries and skeleton fractures, and for identification purposes. Blast injuries typically cause lacerations of the lungs, intestine and major vessels; moreover, hyoid fractures can be documented. Histopathology may help to define blast injuries effectively. Forensic chemistry, toxicology and ballistics provide useful investigative evidence as well as anthropology and genetics. Different forensic topics regarding explosions are discussed through five possible scenarios that forensic pathologists may come across. Scenarios include self-inflicted explosion deaths, domestic explosions, work-related explosions, terrorist events, and explosions caused by accidents involving heavy vehicles.

Conclusion

The scenarios presented offer a useful instrument to avoid misinterpretations and evaluation errors. Procedural notes and technical aspects are provided to the readers, with an insight on collaboration with other forensic experts.

Computerized delineation of the teeth and comparison with a smiling photograph: identification of a body skeletonized by cadaverous ichthyofauna action

Amazonian's forensic experts usually experience considerable difficulties in the identification of drowned bodies rescued from the rivers of the Amazon basin, since they are frequently found skeletonized by the action of the cadaverous ichthyofauna. In these circumstances, especially when the soft tissues are completely absent, bones and teeth may represent the unique source of information for the identification of the body. This work reports a case of positive identification of a body skeletonized by scavenger ichthyofauna. The identification was performed by comparing computerized delineation of the dental characteristics of the cadaver with those observed in a smiling photograph of the victim. This report also highlights the ferocity of Cetopsis candiru (candiru cobra), Cetopsis coecutiens (candiru-açu) and Calophysus macropterus (piracatinga).

Twenty-five years of unidentified bodies: an account from Milano, Italy

The identification of decedents has always been a central issue in forensic pathology, for ethical, criminal, and administrative reasons, but today, it needs more attention due to issues related not only to migration but also to the weakening of family ties. This article presents a descriptive study discussing the Italian regulatory situation developed in the last decade to face the many identification issues, with all its improvements and flaws. Hence, data gathered in 25 years of at the Institute of Legal Medicine of Milan and the epidemiology of unidentified decedents are illustrated. Briefly, from 1995 to 2019, the number of unidentified human remains with no identity or requesting verification of identity amounts to 726, i.e., 3% circa of all autopsies performed at the Institute, with an average of 29 individuals per year. In total, 528 (72.7%) individuals were successfully identified, 100 (13.8%) remained without an identity, and 98 (13.5%) individuals remained with suspected yet unconfirmed identities. Percentages for each identification technique are displayed, with insight into the role of forensic anthropology and odontology compared to genetics, and into the misuse of non-scientific methods allowed by Public Prosecutors. All the data is compared, as much as possible, with the very few recent studies concerning the problem worldwide. Finally, the article aims to show the Italian experience in dealing with unidentified bodies, in order to provide food for thought for other countries toward a discussion regarding a global issue which is sometimes taken for granted and underestimated.

Human identification: a review of methods employed within an Australian coronial death investigation system

Whilst many identification methods have been widely described and discussed in the literature, and considered in disaster and humanitarian contexts, there has been limited reporting and evaluation of the identification methods used in domestic medico-legal death investigation contexts. The aim of this study was to evaluate the identification methods utilised at the Victorian Institute of Forensic Medicine (VIFM), which forms part of a coronial medico-legal death investigation system. The method of identification and time taken to complete the identification were reviewed for all cases admitted to the VIFM over a five-year period from 1 July 2015 to 30 June 2020. The majority, 91%, of individuals admitted to the VIFM were visually identified. The remaining 9% of cases required identification by primary methods (i.e. fingerprints, DNA or dental) or, when those methods were not possible, by secondary methods (i.e. circumstantial). Visual identifications were the timeliest, taking an average of 1.5 days, whilst primary identification methods required an average of 5 days to complete. The triaging of identification methods, dependent on the case context, body preservation, availability of ante-mortem data, legal requirements and admissibility of the method, are determined by identification coordinators within the Human Identification Service (HIS) to ensure the most appropriate and timely method is employed. This review of human identification methods provides the foundation for future analyses to compare workflow processes and improve identification methods utilised in domestic medico-legal contexts.

Strengthening the role of forensic anthropology in personal identification: Position statement by the Board of the Forensic Anthropology Society of Europe (FASE)

In this position statement, the Board members of the Forensic Anthropology Society of Europe (FASE) argue that forensic anthropology methods can be used as means of personal identification, particularly in situations with limited availability of traditional identification methods (i.e. dactyloscopy, odontology, and molecular genetic analysis). This statement has been issued taking into account the international migration crises related to thousands of deaths worldwide, in which the utility of these traditional means of identification has been sporadic to non-existent. The statement is however not limited to deaths related to the migration crises, as similar problems may occur in fatalities en masse such as in natural disasters and armed conflicts, and on a smaller scale in cases of homeless or otherwise socioeconomically disadvantaged persons. The number of reports on personal identification based on sound anthropological methodology is increasing in the scientific literature. However, more research is needed to develop evidence-based standard operating procedures and statistical frameworks. It remains essential to raise awareness among forensic practitioners, law enforcement, and judiciary professionals on the utility of forensic anthropology in cases where it can provide sufficient information for identification.

The use of tattoos to identify unknown bodies

The identification of unknown bodies is the fulfilment of a moral obligation towards the deceased, serves to maintain legal security within a society, and gives families the certainty they need to mourn. Taking into account respective local conditions, the aim should always be to achieve a secure and quick identification. To achieve this goal, a functioning cooperation between investigating authorities and forensic sciences is essential.

The main objective of this study was to clarify the potential role of tattoos in the identification process of unknown deceased persons in the state of Jalisco, Mexico. Post-mortem data of 2045 bodies from the Instituto Jaliscience de Ciencias Forenses in Guadalajara were evaluated.

Of the deceased 46% were tattooed (male: 47%, female: 39%), with 29% of all bodies (male: 29%, female: 26%) showing tattoos at body locations usually visible in everyday life (i.e. head and neck, forearms and hands). The male bodies were most frequently tattooed on the shoulders and upper arms, followed by the forearms and hands and the torso. Female bodies mostly showed tattoos on the forearms and hands, followed by the torso and legs.

Taking local tattooing habits into account, the authors developed a classification for tattoo motives. With decreasing frequency, the following keywords could be assigned to the motives: letters and/or numbers, human, symbol (other), plant, symbol (religious), animal, object, tribal/ornament/geometry, fantasy/demon/comic, other.

Results of the study indicate the great importance of tattoos as a possible mean of identification in Jalisco, Mexico – either as a stand-alone identification method, as a complementary tool or for planning and prioritizing subsequent investigations.

Simple, Frequent Indicator for Personal Identification-Postmortem and Antemortem Abdominal Computed Tomography Findings of a Charred Body

Postmortem personal identification in forensic science is performed using various methods. However, severely burnt bodies are hard to identify using odontological or skeletal features because of carbonization, and sometimes DNA profiling is impracticable because of the unavailability of the relatives. We present a case of a burn victim found after a house fire. Personal identification was attempted, but the body was heavily charred to the bones and the use of physical appearance was impracticable. There were no known relatives or personal belongings of the deceased for comparison of DNA typing. We obtained a series of abdominal computed tomography (CT) scans taken antemortem and found bilateral multiple renal cysts, left renal artery calcification, and a big right inguinal hernia, which matched the deceased's postmortem CT findings and autopsy findings. To date, studies of identification by CT have acted for a rise in precision, but they require complicated calculation or high graphical methods. Calcification of the arteries or renal cysts seen in our case are very common lesions present in many adults with abundant variation; thus, they may be helpful as simple indicators for identification.