Developing a new scoring method to evaluate human decomposition in a humid,continental (Dfb) climate in Quebec

The published literature shows a lack of methods to evaluate the patterns and extent of decomposition of human remains and to estimate the post-mortem interval (PMI) in humid, continental (Dfb) climates such as Quebec. The aim of this study was to address this gap in the current knowledge base by providing the first observations from human corpses studied under controlled conditions in Quebec. A 12-month study was conducted at the site for Research in Experimental and Social Thanatology; the first human taphonomy facility in Canada. Six human donors with known time of death were deposited across spring (n = 1), summer (n = 3), and autumn (n = 2) 2021. The lack of suitability of the total body score method to evaluate the extent of decomposition at the facility prompted the development of a new scoring system based on the macromorphoscopic changes observed. The scoring system was applied to the donors to evaluate decomposition throughout seasons. All donors followed comparable decomposition trajectories, regardless of the season of deposition. Eighty-five percent of taphonomic patterns appeared in the first 25 experimental days or 5000 Kelvin accumulated degree days (350 ADD). Extensive desiccation of tissues was observed at a median of 21 experimental days across donors, resulting in a plateau within decomposition with no extensive skeletonization. To the authors' knowledge, this is the first published report of experimentally observed desiccation in such a form in a Dfb climate. This study provides new data on the types of decomposition patterns to expect in forensic investigations in southern Quebec and comparable climates.     

The Effect of Body Mass on Outdoor Adult Human Decomposition

Forensic taphonomy explores factors impacting human decomposition. This study investigated the effect of body mass on the rate and pattern of adult human decomposition. Nine males and three females aged 49–95 years ranging in mass from 73 to 159 kg who were donated to the Complex for Forensic Anthropology Research between December 2012 and September 2015 were included in this study. Kelvin accumulated degree days (KADD) were used to assess the thermal energy required for subjects to reach several total body score (TBS) thresholds: early decomposition (TBS ≥6.0), TBS ≥12.5, advanced decomposition (TBS ≥19.0), TBS ≥23.0, and skeletonization (TBS ≥27.0). Results indicate no significant correlation between body mass and KADD at any TBS threshold. Body mass accounted for up to 24.0% of variation in decomposition rate depending on stage, and minor differences in decomposition pattern were observed. Body mass likely has a minimal impact on postmortem interval estimation.     

The Effects of Sharp‐Force Thoracic Trauma on the Rate and Pattern of Decomposition

Given the multiple factors that may alter the rate of decomposition, one of the more difficult tasks that anthropologists and pathologists face is determining of the postmortem interval (PMI). While trauma has been widely accepted as being among those factors, recent published studies have contradicted this premise. However, major issues exist with these studies. Consequently, this study was designed to simulate a more realistic setting in an effort to settle this discrepancy in the literature. This study utilized eight porcine remains; three of which received incised wounds penetrating the thoracic cavity, three others received nonpenetrating wounds, and two were designated nontrauma controls. Measurements included evaluating the total body score (TBS) on temporal and accumulated degree days (ADD). Using a two‐way repeated measures ANOVA, the results of this study found that while trauma does have an influence in the pattern of decomposition, it does not influence the rate of decomposition.     

The Effect of Clothing on the Rate of Decomposition and Diptera Colonization on Sus scrofa Carcasses

Twenty Sus scrofa carcasses were used to study the effect the presence of clothing had on decomposition rate and colonization locations of Diptera species; 10 unclothed control carcasses were compared to 10 clothed experimental carcasses over 58 days. Data collection occurred at regular accumulated degree day intervals; the level of decomposition as Total Body Score (TBS_surf), pattern of decomposition, and Diptera present was documented. Results indicated a statistically significant difference in the rate of decomposition, (t₄₂₇ = 2.59, p = 0.010), with unclothed carcasses decomposing faster than clothed carcasses. However, the overall decomposition rates from each carcass group are too similar to separate when applying a 95% CI, which means that, although statistically significant, from a practical forensic point of view they are not sufficiently dissimilar as to warrant the application of different formulae to estimate the postmortem interval. Further results demonstrated clothing provided blow flies with additional colonization locations.     

Stature and Body Weight Estimation from Various Footprint Measurements Among Egyptian Population

Abstract: Analysis of footprints can reveal very important clues which can be used as a forensic evidence and help in the estimation of stature and body weight of an individual. In this work, bilateral footprints were obtained from 50 male Egyptian medical students ranging in age between 18 and 25. Nine measurements were taken on each footprint. The result revealed significant bilateral asymmetry (p < 0.001) except foot breadth at ball. The significant and positive highest correlation coefficients with stature were shown by toe‐5 length on right side (R = 0.58) and with body weight by foot breadth at ball on left side (R = ?0.52). Regression equations presented smaller standard errors of estimate (3.52–4.69) in determination of stature than those in estimation of body weight (4.05–5.28). In conclusion, this study has provided equations that help to estimate stature and body weight from footprint measurements among Egyptians.     

Fatal Falls from Height in Taiwan

This study conducts an investigation of fatal falls from height, examines gender differences, and compares our findings with those of Western countries. We review deaths in Taiwan caused by falls from height that underwent forensic autopsy from 1994 to 2010. Among the examined cases, 182 were suicide, 156 were accidents, and 18 were homicides. Men who fell from greater heights had a lower probability of fatal head trauma (p = 0.045), and women exhibited a lower fatal head trauma rate when falling from heights of between 10 and 25 m in accident group (p = 0.003). There was no significant difference between cases of falling from greater and lower heights within the suicide group (p = 0.834). Psychiatric illness was only reported in 20.3% and 28.8% cases in suicide and accident groups. Only in male cases was the use of psychotropic substances higher in the suicide groups than in the accident groups (p = 0.047).     

Potential Use of Bacterial Community Succession in Decaying Human Bone for Estimating Postmortem Interval,,

Bacteria are taphonomic agents of human decomposition, potentially useful for estimating postmortem interval (PMI) in late‐stage decomposition. Bone samples from 12 individuals and three soil samples were analyzed to assess the effects of decomposition and advancing time on bacterial communities. Results indicated that partially skeletonized remains maintained a presence of bacteria associated with the human gut, whereas bacterial composition of dry skeletal remains maintained a community profile similar to soil communities. Variation in the UniFrac distances was significantly greater between groups than within groups (p < 0.001) for the unweighted metric and not the weighted metric. The members of the bacterial communities were more similar within than between decomposition stages. The oligotrophic environment of bone relative to soft tissue and the physical protection of organic substrates may preclude bacterial blooms during the first years of skeletonization. Therefore, community membership (unweighted) may be better for estimating PMI from skeletonized remains than community structure (weighted).     

The Influence of Preburial Insect Access on the Decomposition Rate

Abstract: This study compared total body score (TBS) in buried remains (35 cm depth) with and without insect access prior to burial. Sixty rabbit carcasses were exhumed at 50 accumulated degree day (ADD) intervals. Weight loss, TBS, intra‐abdominal decomposition, carcass/soil interface temperature, and below‐carcass soil pH were recorded and analyzed. Results showed significant differences (p << 0.001) in decomposition rates between carcasses with and without insect access prior to burial. An approximately 30% enhanced decomposition rate with insects was observed. TBS was the most valid tool in postmortem interval (PMI) estimation. All other variables showed only weak relationships to decomposition stages, adding little value to PMI estimation. Although progress in estimating the PMI for surface remains has been made, no previous studies have accomplished this for buried remains. This study builds a framework to which further comparable studies can contribute, to produce predictive models for PMI estimation in buried human remains.     

Citrate Content of Bone for Time Since Death Estimation: Results from Burials with Different Physical Characteristics and Known PMI

A recently introduced method to determine the postmortem interval (PMI) based on quantification of the citrate content in bone was applied on the temporal bones and femora of 20 individuals buried in wooden coffins (WO) and body bags (BB), respectively. Concerning known vs. calculated PMI, a significant difference between the temporal and the femur bone samples of the same individuals was observed in the BB group (p = 0.012). In contrast, differences were insignificant for the WO group (p = 0.400). Moreover, similar levels of underestimation of PMIs resulted from the analysis of the femora for both burial groups (p = 0.247). Also, there was consistently less citrate preserved in the flat temporal bones as compared to the femora, indicating that the cortical layer of the long bones should be preferentially employed for citrate‐based PMI estimations. The results call for additional research on subsurface‐buried and surface‐deposited remains to enhance the accuracy of the published PMI equation.     

The Effect of Repeated Physical Disturbance on Soft Tissue Decomposition—Are Taphonomic Studies an Accurate Reflection of Decomposition?*

Although the relationship between decomposition and postmortem interval has been well studied, almost no studies examined the potential effects of physical disturbance occurring as a result of data collection procedures. This study compares physically disturbed rabbit carcasses with a series of undisturbed carcasses to assess the presence and magnitude of any effects resulting from repetitive disturbance. Decomposition was scored using visual assessment of soft tissue changes, and numerical data such as weight loss and carcass temperature were recorded. The effects of disturbance over time on weight loss, carcass temperature, soil pH and decomposition were studied. In addition, this study aimed to validate some of the anecdotal evidence regarding decomposition. Results indicate disturbance significantly inversely affects both weight loss and carcass temperature. No differences were apparent between groups for soil pH change or overall decomposition stage. An insect-mediated mechanism for the disturbance effect is suggested, along with indications as to why this effect may be cancelled when scoring overall decomposition.     

Human Versus Animal: Contrasting Decomposition Dynamics of Mammalian Analogues in Experimental Taphonomy

Taphonomic studies regularly employ animal analogues for human decomposition due to ethical restrictions relating to the use of human tissue. However, the validity of using animal analogues in soil decomposition studies is still questioned. This study compared the decomposition of skeletal muscle tissues (SMTs) from human (Homo sapiens), pork (Sus scrofa), beef (Bos taurus), and lamb (Ovis aries) interred in soil microcosms. Fixed interval samples were collected from the SMT for microbial activity and mass tissue loss determination; samples were also taken from the underlying soil for pH, electrical conductivity, and nutrient (potassium, phosphate, ammonium, and nitrate) analysis. The overall patterns of nutrient fluxes and chemical changes in nonhuman SMT and the underlying soil followed that of human SMT. Ovine tissue was the most similar to human tissue in many of the measured parameters. Although no single analogue was a precise predictor of human decomposition in soil, all models offered close approximations in decomposition dynamics.     

DEET (N,N‐Diethyl‐meta‐toluamide) Induced Delay of Blowfly Landing and Oviposition Rates on Treated Pig Carrion (Sus scrofa L.)

Abstract: The question of whether the insect repellent N,N‐Diethyl‐meta‐toluamide (DEET) affected fly attraction, oviposition, and larval development was investigated; in part, to determine whether the common habit of wearing DEET as a repellent could affect the rate of human decomposition. Experiments using pig surrogates of human decedents were carried out in a rural environment. Dead piglets were sprayed with DEET, and fly behavior, colonization levels, and maggot development were compared with those in nonsprayed controls. Piglets treated with DEET experienced significant delays in fly visitation and oviposition and delayed appearance of each larval instar, as well as reduced total larval numbers (p < 0.01 for all variables), with subsequently reduced decomposition (p < 0.05). Such changes in fly behavior and larval population development would significantly impact the estimation of the period following the death from entomological evidence in decedents wearing DEET at the time of their death.     

Decomposition Rate and Pattern in Hanging Pigs

Accurate prediction of the postmortem interval requires an understanding of the decomposition process and the factors acting upon it. A controlled experiment, over 60 days at an outdoor site in the northwest of England, used 20 freshly killed pigs (Sus scrofa) as human analogues to study decomposition rate and pattern. Ten pigs were hung off the ground and ten placed on the surface. Observed differences in the decomposition pattern required a new decomposition scoring scale to be produced for the hanging pigs to enable comparisons with the surface pigs. The difference in the rate of decomposition between hanging and surface pigs was statistically significant (p = 0.001). Hanging pigs reached advanced decomposition stages sooner, but lagged behind during the early stages. This delay is believed to result from lower variety and quantity of insects, due to restricted beetle access to the aerial carcass, and/or writhing maggots falling from the carcass.     

Examination of Hacking and Blunt Force Skeletal Trauma

Hacking trauma is prevalent in forensic cases involving genocide and dismemberment, but research into the identification of this type of trauma is lacking. The present study examines characteristics of hacking and blunt force skeletal trauma in order to determine if there is a point at which blunt force trauma becomes distinguishable from hacking trauma. Ten implements with a range of blade angles (i.e., the striking surface of the implement) were used in conjunction with a controlled-force hacking device to impact 100 limb bones of white-tailed deer (Odocoileus virginianus). Observations of the trauma included the occurrence and degree of fragmentation, the entrance widths of the impacts, and composite scores of six hacking characteristics, especially the distinctive V-shaped kerf. ANOVA tests and regression analyses were used to assess the relationships between these characteristics and the blade angles. A significant relationship (p-value = 0.011) was found between the composite hacking scores and the blade angles, indicating that blunt force and hacking trauma can be distinguished. The entrance widths of the impacts exhibited a significant relationship with the blade angles (p-value = 0.037). There was also a significant relationship between the visibility of a V-shaped kerf in the bones (p-value = 0.003), with visibility decreasing around the 60° blade angle. These data should assist in establishing guidelines to differentiate hacking and blunt force skeletal trauma in cases where the implement is on a spectrum between sharp and blunt.     

Subway Train‐Related Fatalities in New York City: Accident versus Suicide*

Abstract: We examined the characteristics of subway train‐related fatalities in New York City between Jan. 1, 2003 and May 31, 2007 in order to determine which factors are useful in differentiating accident from suicide. Subway train‐related deaths with homicide and undetermined manners also are included. During this period, there were 211 subway train‐related fatalities. The manners of death were: suicide (n = 111), accident (n = 76), undetermined (n = 20), and homicide (n = 4). The causes of death were blunt trauma (n = 206) and electrocution (n = 5). Torso transection and extremity amputation were more frequent in suicides. Antidepressant medications were more frequently detected in suicides, whereas cocaine and ethanol were more frequent in accidents. However, autopsy findings should be weighed in the context of the entire evaluation along with other circumstantial and investigative findings. In unwitnessed deaths where additional information is unavailable or discrepant, the most appropriate manner of death usually is undetermined.     

Decomposition and Arthropod Succession in Whitehorse,Yukon Territory,Canada

Forensic arthropod succession patterns are known to vary between regions. However, the northern habitats of the globe have been largely left unstudied. Three pig carcasses were studied outdoors in Whitehorse, Yukon Territory. Adult and immature insects were collected for identification and comparison. The dominant Diptera and Coleoptera species at all carcasses were Protophormia terraneovae (R‐D) (Fam: Calliphoridae) and Thanatophilus lapponicus (Herbst) (Fam: Silphidae), respectively. Rate of decomposition, patterns of Diptera and Coleoptera succession, and species dominance were shown to differ from previous studies in temperate regions, particularly as P. terraenovae showed complete dominance among blowfly species. Rate of decomposition through the first four stages was generally slow, and the last stage of decomposition was not observed at any carcass due to time constraints. It is concluded that biogeoclimatic range has a significant effect on insect presence and rate of decomposition, making it an important factor to consider when calculating a postmortem interval.     

Differential decomposition patterns in charred versus un-charred remains

Although researchers have examined many aspects of fire modification, the rate and pattern of decomposition in charred remains have not been studied previously. This study utilized 48 domestic pigs, divided into 24 charred (head, neck, and limbs burned to Crow-Glassman level 1 and torso to level 2) and 24 un-charred pig carcasses. Decomposition of control carcasses was scored at 50 accumulated degree days (ADD) intervals, and charred carcasses were also observed and photographed at this time. A Charred Body Scale was subsequently created, and charred carcasses were scored retrospectively for the same ADD intervals. Analysis using a mixed-effect repeated measures model indicated that, while decomposition rate was not statistically different between the two groups (p = 0.2692), the charred remains initially displayed an ostensibly more advanced pattern. Body regions displaying significant charring decomposed at a faster rate (p < 0.001), while areas with very light levels of charring decomposed at a significantly slower rate (p < 0.001).     

An Examination of the Transition of Fracture Characteristics in Long Bones from Fresh to Dry in Central Florida: Evaluating the Timing of Injury

It is important to conduct timing of injury research analyzing fracture characteristics at known postmortem intervals (PMI) because bone can retain fresh characteristics throughout the PMI. Defleshed pig (Sus scrofa) long bones were fractured weekly in two environments (full sun and shade) over 14 weeks in Central Florida and fracture characteristics were categorized (N = 136) for analysis. Results of analysis of variance (ANOVA) using time in weeks (PMI) as a dependent variable indicate significant relationships between PMI and Fracture Angle (p < 0.001), Fracture Surface (p < 0.001), and Fracture Outline (p < 0.001). Fracture characteristics associated with perimortem trauma (smooth Fracture Surfaces and curved or V‐shaped Fracture Outlines) were commonly observed. Analysis of fracture characteristics for each environment demonstrated similar patterns. Overall, the loss of only fresh fracture characteristics for each bone was noted earlier in the PMI for the Central Florida region than previously reported.