Examining thermally induced movement of the fatal fire victim.

Investigating a fatal fire scene comprises analysis not only of the fire's development to identify the point of fire origin and ignition source, but analysis of a victim's position and their relationship within the scene. This work presents both qualitative and quantitative results from experimentation investigating the effect of a real fire environment on the human body, and how the position of a victim at the post burn investigation stage may be significantly different to the position at fire ignition. Qualitative observations were undertaken on the burning of 39 compartment and vehicle scenes from ignition through to suppression, each containing a human cadaver. The results of analysis question the validity of previous work based on cremation observations. Quantitative results were produced by recording 13 points on the body on the X, Y and Z axis, both pre and post burn on a smaller dataset of ten compartment burns. Results have enabled a more robust assessment of thermally induced movement of the body within the scene along each axis, evidencing that pugilism is not the universal reaction of the fatal victim to thermal exposure, with extension of the upper limbs far more common than has been previously reported.

Examination of misconceptions surrounding fatal fire victims.

Fire deaths are not unusual in forensic investigative practice but due to the destructive nature of fire they are often very difficult to investigate. With the need to identify the deceased and the events surrounding the manner and cause of death, knowledge of thermally induced alteration to the human body is important. Within the fire investigation community, a number of misconceptions have been present for years regarding the protrusion of the tongue as an indicator of life during the fire, and fractured skulls as the result of brains boiling and skulls exploding. This work presents qualitative analysis on the experimental burning of 42 unembalmed human donated cadavers by the San Luis Obispo Strike Team (SLOFIST) on their annual Forensic Fire Death Investigation Course (FFDIC) between 2017 and 2019. Prior to burning, the position of the tongue within the dental arch was confirmed and sharp, blunt, surgical and gunshot trauma to the cranium documented. Temperature was recorded from ignition through to suppression with thermocouples present both within the scene and the body. Post burn analysis on the position of the tongue, observation of cranial fractures and presence of brain tissue were recorded and analysed in conjunction with thermocouple data, fire scene dynamics and body demographics. The results provide a more comprehensive understanding of the thermal environmental factors involved in producing the phenomena that facilitate these misconceptions, identifying that a more thorough understanding of individual fire scenes and their development is essential when interpreting alteration and injury to the body of the fatal fire victim.

Survival of sharp force trauma in burnt bones: effects of environmental factors.

This study investigates how environmental variables, such as temperature and rainfall, affect previously induced cut marks on burnt bones. This research used non-serrated and serrated blade knives to inflict trauma on Sus scrofa ribs (n = 240). The bones were later burnt and left for 1 month in a taphonomic experimental facility. Qualitative and quantitative examinations were conducted using macroscopic and microscopic techniques to assess specific characteristics of the cut marks. Any changes to the dimension and morphology of the cut marks as well as their level of fragmentation were recorded.This study has led to three important outcomes: (1) identification of pre-existing cut marks is possible in reconstructed burnt bone fragments; (2) cut marks from different types of knife blades showed dissimilar responses to heat and the environment; and (3) specific environmental variables affect burnt bone fragmentation. These results have implications for trauma analysis on burnt remains in forensic anthropology casework.

Forensic DNA extraction methods for human hard tissue: A systematic literature review and meta-analysis of technologies and sample type.

DNA identification of human remains has a valuable role in the field of forensic science and wider. Although DNA is vital in identification of unknown human remains, post-mortem environmental factors can lead to poor molecular preservation. In this respect, focus has been placed on DNA extraction methodologies for hard tissue samples, as these are the longest surviving. Despite decades of research being conducted on DNA extraction methods for bone and teeth, little consensus has been reached as to the best performing. Therefore, the aim of this study was to conduct a thorough systematic literature review to identify potential DNA extraction technique(s) which perform optimally for forensic DNA profiling from hard tissue samples. PRISMA guidelines were used, by which a search strategy was developed. This included identifying databases and discipline specific journals, keywords, and exclusion and inclusion criteria. In total, 175 articles were identified that detailed over 50 different DNA extraction methodologies. Results of the meta-analysis conducted on 41 articles - meeting further inclusion criteria - showed that statistically significant higher DNA profiling success was associated with solid-phase magnetic bead/resin methods. In addition, incorporating a demineralisation pre-step resulted in significantly higher profiling successes. For hard tissue type, bone outperformed teeth, and even though dense cortical femur samples were more frequently used across the studies, profiling success was comparable, and in some cases, higher in cancellous bone samples. Notably, incomplete data sharing resulted in many studies being excluded, thus an emphasis for minimum reporting standards is made. In conclusion, this study identifies strategies that may improve success rates of forensic DNA profiling from hard tissue samples. Finally, continued improvements to current methods can ensure faster times to resolution and restoring the identity of those who died in obscurity.

Solving the inverse problem of post-mortem interval estimation using Bayesian Belief Networks.

Bayesian Belief Networks (BBNs) can be applied to solve inverse problems such as the post-mortem interval (PMI) by a simple and logical graphical representation of conditional dependencies between multiple taphonomic variables and the observable decomposition effect. This study is the first cross-comparison retrospective study of human decomposition across three different geographical regions. To assess the effect of the most influential taphonomic variables on the decomposition rate (as measured by the Total Decomposition Score (TDS)), decomposition data was examined from the Forensic Anthropology Research Facility at the University of Tennessee (n = 312), the Allegheny County Office of the Medical Examiner in Pittsburgh, US (n = 250), and the Crime Scene Investigation department at Southwest Forensics in the UK (n = 81). Two different BBNs for PMI estimations were created from the US and the UK training data. Sensitivity analysis was performed to identify the most influential parameters of TDS variance, with weaker variables (e.g., age, sex, clothing) being excluded during model refinement. The accuracy of the BBNs was then compared by additional validation cases: US (n = 28) and UK (n = 10). Both models conferred predictive power of the PMI and accounted for the unique combination of taphonomic variables affecting decomposition. Both models had a mean posterior probability of 86% (US) and 81% (UK) in favor of the experimental hypothesis (that the PMI was on, or less than, the prior last known alive date). Neither the US nor the UK datasets represented any cases below 'moderate' support for the value of PMI evidence. By applying coherent probabilistic reasoning to PMI estimations, one logical solution is provided to model the complexities of human decomposition that can quantify the combined effect of several uncertainties surrounding the PMI estimation. This approach communicates the PMI with an associated degree of confidence and provides predictive power on unknown PMI cases.

The application of dual energy X-ray soil screening in forensic archaeology.

The need to forensically search soil for small artefacts at a burial site or traces of evidence in a deposition site is a common task shared by investigators and forensic archaeologists. In forensic casework, the importance of finding small pieces of evidence, such as personal effects or ballistic fragments, cannot be overstated as it can assist in the positive identification of the deceased, give an insight into the manner and cause of death, and identify any perpetrators. The soil search methods known as wet and dry sieving, are cumbersome, time-consuming and have limited success for some soil types. This often leads to the decision not to search, resulting in missed opportunities to identify potential evidence. The primary aim of this study was to investigate if a dual energy X-ray baggage scanner could be used to search for items of potential forensic interest in soil. A trial was conducted using a Smiths Detection ScanTrailer 100100 V-2is mobile X-ray inspection system to establish if it could be used to detect organic, inorganic, and metallic items located within soil. The soil type and natural variables such as water and organic content were adjusted to simulate different environments. The baggage scanner was found to provide a quick and easy way to detect items contained within various soil types, particularly in a sand rich matrix. It is estimated that using this method to search 1 m3 of soil, when broken down into samples that are < 13 cm in depth, would take around one hour to complete, compared with 100 to 150 person-hours by manual sieving. This is believed to be the first use of dual energy X-ray technology for this purpose and shows the potential for further research and use of this method in forensic archaeology.

New Trends in Immunohistochemical Methods to Estimate the Time since Death: A Review.

The identification of a reliable and accurate post-mortem interval (PMI) is a major challenge in the field of forensic sciences and criminal investigation. Several laboratory techniques have recently been developed that offer a better contribution to the estimation of PMI, in addition to the traditional physical or physico-chemical (body cooling, lividity, radiocarbon dating, rigor mortis), chemical (autolysis), microbiological (putrefaction), entomological, as well as botanical parameters. Molecular biology (degradation pattern of macromolecules such as proteins, DNA, RNA), biochemical analysis of biological fluids (such as blood, cerebrospinal fluid, and vitreous humor), and immunohistochemistry are some of the most recent technological innovations. A systematic review of the literature was performed with the aim of presenting an up-to-date overview on the correlation between the immunohistochemical (IHC) expression of specific antigenic markers at different PMIs. The systematic review was performed according to PRISMA guidelines. Scopus and PubMed were used as search engines from January 1, 1998 to March 1, 2022 to evaluate the effectiveness of immunohistochemistry in estimating PMI. The following keywords were used: (immunohistochemical) OR (immunohistochemistry) AND (time since death) OR (post-mortem interval) OR (PMI). A total of 6571 articles were collected. Ultimately, 16 studies were included in this review. The results of this systematic review highlighted that IHC techniques, in association with traditional methods, add, in Bayesian terms, additional information to define a more accurate time of death and PMI. However, current IHC results are numerically limited and more data and studies are desirable in the near future.

How Do Drugs Affect the Skeleton? Implications for Forensic Anthropology.

Forensic anthropologists rely on a number of parameters when analyzing human skeletal remains to assist in the identification of the deceased, predominantly age-at-death, sex, stature, ancestry or population affinity, and any unique identifying features. During the examination of human remains, it is important to be aware that the skeletal features considered when applying anthropological methods may be influenced and modified by a number of factors, and particular to this article, prescription drugs (including medical and non-medical use) and other commonly used drugs. In view of this, this paper aims to review the medical, clinical and pharmacological literature to enable an assessment of those drug groups that as side effects have the potential to have an adverse effect on the skeleton, and explore whether or not they can influence the estimation of age-at-death, sex and other indicators of the biological profile. Moreover, it may be that the observation of certain alterations or inconsistencies in the skeleton may relate to the use of drugs or medication, and this in turn may help narrow down the list of missing persons to which a set of human remains could belong. The information gathered from the clinical and medical literature has been extracted with a forensic anthropological perspective and provides an awareness on how several drugs, such as opioids, cocaine, corticosteroids, non-steroidal anti-inflammatory drugs, alcohol, tobacco and others have notable effects on bone. Through different mechanisms, drugs can alter bone mineral density, causing osteopenia, osteoporosis, increase the risk of fractures, osteonecrosis, and oral changes. Not much has been written on the influence of drugs on the skeleton from the forensic anthropological practitioner perspective; and this review, in spite of its limitations and the requirement of further research, aims to investigate the current knowledge of the possible effects of both prescription and recreational drugs on bones, contributing to providing a better awareness in forensic anthropological practice and assisting in the identification process of the deceased.

A retrospective comparative study to evaluate the reliability of post-mortem interval sources in UK and US medico-legal death investigations.

Post-mortem interval (PMI) information sources may be subject to varying degrees of reliability that could impact the level of confidence associated with PMI estimations in forensic taphonomy research and in the practice of medico-legal death investigation. This study aimed to assess the reliability of PMI information sources in a retrospective comparative analysis of 1813 cases of decomposition from the Allegheny County Office of the Medical Examiner in Pittsburgh, US (n = 1714), and the Crime Scene Investigation department at Southwest Forensics in the UK (n = 99). PMI information sources were subjected to a two-stage evaluation using an adapted version of the 3x5 aspects of the UK police National Intelligence Model (NIM) to determine the confidence level associated with each source. Normal distribution plots were created to show the distribution frequency of the dependent variables (decomposition stage and source evaluation) by the independent variable of PMI. The manner, location, and season of death were recorded to ascertain if these variables influenced the reliability of the PMI. A confidence matrix was then created to assess the overall reliability and provenance of each PMI information source. Reliable PMI sources (including forensic specialists, missing persons reports, and digital evidence) were used across extensive PMI ranges (1 to 2920 days in the US, and 1 to 240 days in the UK) but conferred a low incidence of use with forensic specialists providing a PMI estimation in only 35% of all homicide cases. Medium confidence PMI sources (e.g., last known social contact) accounted for the majority of UK (54%, n = 54) and US (82%, n = 1413) cases and were associated with shorter PMIs and natural causes of death. Low confidence PMI sources represented the lowest frequencies of UK and US cases and exclusively comprised PMI information from scene evidence. In 96% of all cases, only one PMI source was reported, meaning PMI source corroboration was overall very low (4%). This research has important application for studies using police reports of PMI information to validate PMI estimation models, and in the practice of medico-legal death investigation where it is recommended that i) the identified reliable PMI sources are sought ii) untested or unreliable PMI sources are substantiated with corroborating PMI information, iii) all PMI sources are reported with an associated degree of confidence that encapsulates the uncertainty of the originating source.

Physicochemical Changes in Bone Bioapatite During the Late Postmortem Interval Pre- and Post-Burning.

Postmortem chemical transformation of bone bioapatite can take place during early diagenesis, resulting in a more thermodynamically stable mineral phase. This paper examines the impact of a one year postmortem interval on unburnt and burnt bone's structural and chemical alterations. This question is of importance for the reconstruction of funerary practices involving cremation in the archaeological record, as well as forensic anthropological investigations. Fleshed pig (Sus scrofa) tibiae were left exposed in a field, then collected at 14, 34, 91, 180, and 365 day intervals prior to being burnt in an outdoor fire (≤750 °C bone temperature). Fresh (fleshed) tibiae acted as unburnt and burnt controls. Also included in the study were two cremated human bone fragments from Middle-Late Neolithic (ca. 3300-2500 BCE) Ireland. Samples were analyzed for major and trace elements using an electron microprobe wavelength dispersive analyzer and molecular structures using Fourier transform infrared spectroscopy. Linear regression, principal component analysis, linear discriminant analysis, and multivariate analysis of variance were performed for statistical analysis. Results indicate that the concentrations of elements associated with extracellular fluid (K, Na, and Cl) change with the postmortem interval (PMI) and survive burning. K values under 0.07 ± 0.01 wt% in the inner and mid-cortical zones of burnt bones suggest that bones were not burnt immediately after death. Using this criterion, results from the archaeological samples would indicate a PMI of at least weeks to months prior to cremation. Ca, P, Fe, Al, Si, and Sr are not significantly altered with burning, and Fe, Al, Si, and Sr are also unaffected by the PMI. In unburnt bones increased crystallinity and carbonate loss are detectable in <1 year, but both are obscured by burning. Structurally, the carbonate to phosphate ratio (C/P), the phosphate high temperature, and cyanamide to phosphate (CN/P) are the most useful ratios for discriminating between unburnt and burnt bones.

Measuring dimensional and morphological heat alterations of dismemberment-related toolmarks with an optical roughness metre.

This experimental study provides a further understanding of the post-burning nature of sharp force trauma. The main objective is to analyse the distortion that fire may inflict on the length, width, roughness, and floor shape morphology of toolmarks induced by four different implements. To this end, four fresh juvenile pig long bones were cut with a bread knife, a serrated knife, a butcher machete, and a saw. A total of 120 toolmarks were induced and the bone samples were thus burnt in a chamber furnace. The lesions were analysed with a 3D optical surface roughness metre before and after the burning process. Afterwards, descriptive statistics and correlation tests (Student's t-test and analysis of variance) were performed. The results show that fire exposure can distort the signatures of sharp force trauma, but they remain recognisable and identifiable. The length decreased in size and the roughness increased in a consistent manner. The width did not vary for the saw, serrated knife, or machete toolmarks, while the bread knife lesions slightly shrunk. The floor shape morphology varied after burning, and this change became more noticeable for the three knives. It was also observed that the metrics of the serrated knife and machete cut marks showed no significant variations. Our results demonstrate that there is a variation in the toolmark characteristics after burning. This distortion is dependent on multiple factors that influence their dimensional and morphological changes, and the preservation of class features is directly reliant upon the weapon employed, the trauma caused, and the burning process conditions.

Knife cut marks inflicted by different blade types and the changes induced by heat: a dimensional and morphological study.

Detailed information on skeletal trauma analysis of burned bone is important to ascertain the manner and cause of death in forensic casework. This research used three different knife types, one with a non-serrated blade, one a fine-serrated blade, and one a coarse-serrated blade, to inflict trauma to manually macerated Sus scrofa ribs (n = 240), and these ribs were later exposed to heat. Qualitative and quantitative analyses were conducted using macroscopic and microscopic techniques to assess specific characteristics of the cut marks. Differences in cut mark dimension and morphology of the ribs were investigated. After heat exposure, the cut marks on the rib samples remained recognisable and did not alter considerably. A level of dimensional and morphological preservation was reliant on the cutting action and the features of the knife blade as well as surrounding bone injury. The cut marks inflicted by the non-serrated blade remained recognisable despite exposure to the burning process. However, the cut marks inflicted by the coarse-serrated blade were likely to change significantly when exposed to heat. This study leads to two important results: (1) identification of pre-existing cut marks prior to heat exposure is possible in reconstructed burned bone fragments, and (2) cut marks from different types of knife blades showed dissimilar responses to heat. The outcomes obtained in this study stressed the need to adopt great care with the effects of heat on skeletal trauma analysis.

Decomposition variability between the scene and autopsy examination and implications for post-mortem interval estimations.

Forensic experts rely on scene and/or autopsy photographs to estimate the post-mortem interval (PMI) when an in-situ assessment of decomposition is unfeasible. The degree of decomposition may vary between the scene and autopsy, which importantly could affect estimations of the unknown PMI in forensic casework. This study aimed to investigate decomposition variability between the scene and autopsy and assess the subsequent effect on the accuracy of PMI estimations. Scene and autopsy photographs from 94 cases with known PMI were used from the Allegheny County Office of the Medical Examiner in Pittsburgh, United States. The total decomposition scoring (TDS) method measured the overall decomposition level, and 28 markers of decomposition were recorded as a percentage of the total body surface area (TBSA). In 60% of cases the TDS had increased at autopsy causing significant overestimations of the autopsy PMI and 86% of decomposition markers varied between the scene and autopsy. Decomposition progressed during mortuary time lags (MTL) of 3-44 h, where bodies were stored in a pre-autopsy refrigerator at 4 °C, suggesting that refrigeration may not always delay decomposition. This research also assisted in validating photographs as a proxy for real-time decomposition assessments. While the autopsy photographs conferred higher quality than the scene photographs, the scene photographs produced more accurate PMI estimations. Forensic experts should exhibit caution when estimating the PMI from autopsy photographs alone, as they may not accurately reflect scene decomposition. To prevent misinterpretation of the PMI estimation, both scene and autopsy photographs should always be requested.

Cut or burnt? - Categorizing morphological characteristics of heat-induced fractures and sharp force trauma.

Distinguishing trauma from heat-induced fractures is a challenge faced by forensic anthropologists and pathologists during medicolegal investigations in which fire has been used by the perpetrators to destroy evidence. This paper aims to validate the provided identification features to distinguish between fire induced alterations and sharp force trauma. A total of 80 cremated adult individuals were used in this paper: 3 recently deceased embalmed cadavers from Cementerio Sur de Madrid for the sharp force trauma experiment in which 55 pre-burning injuries were inflicted using a machete and a serrated knife in different anatomical regions. And 77 cremated individuals from the Forensic Anthropology and Odontology Laboratory osteological collection. Five cremated long bones from this collection were selected, and 10 cuts were manually inflicted using a serrated knife to analyse post-burning trauma. Heat-induced changes and trauma morphologic characteristics were thus documented and analysed. The examination and documentation of morphological traits enabled the production of a heat-induced changes visual guide and a flow-chart. Two intraclass correlation tests were performed to validate the capacity of the observer to distinguish between fire related alterations and toolmarks. The results obtained in the statistical analysis indicate that, even if the toolmarks are visible and recognizable upon macroscopic observation by the observers, some features, such as the step and the transverse fractures can be mistaken with inflicted trauma. The use of the proposed features coupled with careful anthropological examination is recommended and has been found functional for participants with no prior knowledge in the analysis of cremated remains.

The legislation, search, recovery, identification and repatriation of conflict casualties worldwide: Introducing the WWI and WWII Special Issue.

Conflict casualties refer to those individuals who are lost due to military conflict or war. The involvement of forensic archaeologists and anthropologists in the legal search, recovery, documentation, identification, and repatriation/reburial of conflict casualties is well known. Internationally, there are a number of professional organisations who ethically recover and identify these individuals. However, at the same time, some organisations and individuals have raised significant concerns about working in other countries, understanding specific laws and protocols, and how the whole recovery and identification process should be undertaken. Through this special issue, Forensic Science International is interested in promoting these investigative good-practice procedures, illustrated with case studies, and ethical and legal considerations when undertaking and disseminating these humanitarian missions to the wider forensic community. This Special Issue focuses primarily on the First and Second World Wars, yet other conflicts are covered, and includes the views and perspectives from different organisations within specific countries in the format of original papers, commentaries, and case reports. Specifically, these papers include the legislative regulations, information regarding the authorities to be consulted on and who deal with human remains, the organisations and professionals who are involved with the recovery and analysis of human remains, the process of identification, and how this information is disseminated to the public.

Spanish Civil War: The recovery and identification of combatants.

In the context of exhumations of individuals who died during the Spanish Civil War (1936-1939), since the year 2000, over 780 mass graves have been excavated using archaeological methodology and following forensic protocols. Most of the recovered more than 9600 bodies have tended to be from the Republican civil population, the majority having been executed extrajudicially. However, a number of exhumations relate to the remains of soldiers who died in combat. In fact, approximately 100 individual or mass graves have been investigated and exhumed, containing the remains of combatants. These burials tend to be in the same location where they fell, usually in the front line, or close to the field hospitals where they went after being wounded initially. During the recovery of the human remains, a number of artefacts related to the uniform as well as personal effects have been found. An interdisciplinary approach from archaeology, anthropology, genetics, history and other disciplines has enabled the identification of some of these combatants. The aim of this paper is to present the data obtained from these combatants and highlight the work undertaken in Spain, and the efforts by scientists to exhume, identify and return the remains to relatives where possible.

Dental age estimation based on pulp chamber/crown volume ratio measured on CBCT images in a Spanish population.

Dental age estimation in living individuals is one of the most frequent requests undertaken by forensic odontologists. The aim of this study was to estimate the dental age by pulp/tooth volume ratio, as measured on cone beam computed tomography (CBCT) images, in a Spanish population. This study included 313 teeth from 107 adult individuals, 56 females and 51 males with a mean age of 44 ± 14 years. The statistical analysis of the results took account of clustering (multiple teeth in individuals). Linear regression models were constructed on the relationship between pulp/tooth volume ratio and chronological age for each tooth type. The highest coefficient of determination (R2) value was provided by the upper incisors (36.6%), and the difference between chronological and estimated age was less than 5 years in 31.3% of the sample and less than 10 years for 65.7%. CBCT is an accurate imaging technique to measure dental volume with a relatively low radiation dose, and it can be used to assess dental age in living adult individuals. Volumetric changes in the pulp cavity with increasing age proved valuable to estimate dental age in this Spanish population.