Quantifying the Temperature of Maggot Masses and its Relationship to Decomposition

Numerous Calliphoridae species have been observed to form larval aggregations during the feeding stage of development, resulting in localized increases in temperature. This study investigates the relationship between maggot numbers in a mass and heat generation. Single‐species aggregations (Lucilia sericata) of various sizes (50–2500 individuals) were reared in the laboratory at a constant ambient temperature of 22°C. Internal mass temperatures were recorded every 5 min throughout the feeding stage of development. Results showed that mass temperatures increased with mass numbers (p‐value < 0.001), ranging from 2.5 to 14°C above ambient. A minimum mass size of 1200 produced overall temperatures that were significantly warmer than ambient, diverging away from 22°C after c. 26 h. These results indicate that the microclimate of a mass has the potential to differ significantly from ambient, which may be influencing larval development rates and should therefore be factored into mPMI estimates to increase accuracy.     

Forensic Use of A Subtropical Blowfly: The First Case Indicating Minimum Postmortem Interval (mPMI) in Southern Brazil and First Record of Sarconesia Chlorogaster from a Human Corpse

Southern Brazil is unique due to its subtropical climate. Here, we report on the first forensic entomology case and the first record of Sarconesia chlorogaster (Wiedemann) in a human corpse in this region. Flies' samples were collected from a body indoors at 20°C. Four species were found, but only Chrysomya albiceps (Wiedemann) and S. chlorogaster were used to estimate the minimum postmortem interval (mPMI). The mPMI was calculated using accumulated degree hour (ADH) and developmental time. The S. chlorogaster puparium collected was light in color, so we used an experiment to establish a more accurate estimate for time since initiation of pupation where we found full tanning after 3 h. Development of C. albiceps at 20°C to the end of the third instar is 7.4 days. The mPMI based on S. chlorogaster (developmental time until the third instar with no more than 3 h of pupae development) was 7.6 days.     

Do bone elasticity and postmortem interval affect forensic fractographic analyses?

Forensic fractographic features of bone reliably establish crack propagation in perimortem injuries. We investigated if similar fracture surface features characterize postmortem fractures. Experimentally induced peri- and postmortem fractures were used to assess if fractographic features vary as bone elasticity decreases during the postmortem interval (PMI). Thirty-seven unembalmed, defleshed human femoral shafts from males and females aged 33–81 years were fractured at varying PMIs with a drop test frame using a three-point bending setup and recorded with a high-speed camera. Vital statistics, cause of death, PMI length, temperature, humidity, collagen percentage, water loss, fracture energy, and fractography scores were recorded for each sample. Results showed that fractographic features associated with perimortem fractures were expressed in PMIs up to 40,600 accumulated degree hours (ADH), or 60 warm weather days. Hackle was the most consistently expressed feature, occurring in all fractures regardless of ADH. The most variable characteristics were wake features (78.4%) and arrest ridges (70.3%). Collagen percentage did not correlate strongly with ADH (r = −0.04, p = 0.81); however, there was a strong significant correlation between ADH and water loss (r = 0.74, p < 0.001). Multinomial logistic regression showed no association between fractographic feature expression and ADH or collagen percentage. In conclusion, forensic fractographic features reliably determine initiation and directionality of crack propagation in experimentally induced PMIs up to 40,600 ADH, demonstrating the utility of this method into the recent postmortem interval. This expression of reliable fractographic features throughout the early PMI intimates these characteristics may not be useful standalone features for discerning peri- versus postmortem fractures.     

Epiphyseal Union of the Cervical Vertebral Centra: Its Relationship to Skeletal Age and Maturation of Thoracic Vertebral Centra

Epiphyseal union stages for cervical vertebral centra (ring epiphyses) were documented for 55 individuals (females and males, ages 14–27 years) from the Terry Collection, using the Albert and Maples method 1, to examine both its relationship to age at death and to thoracic data collected from the same individuals using the same method. Results showed a moderate correlation between cervical ring union and age (r = 0.63, p = 0.000), and a fairly low correlation between cervical and thoracic ring union (r = 0.41, p = 0.002). Paired samples t‐tests yielded a statistically significant difference between cervical and thoracic union mean values (p = 0.01). Union progressed earlier in cervical vertebrae and in females. Results indicated fairly substantial variation in both sexes. Findings may serve as a basic guideline for estimating a general age range at death for unknown skeletal remains and to corroborate findings from other skeletal age indicators.     

Forensic Entomology and the Estimation of the Minimum Time Since Death in Indoor Cases

Eight cases that occurred indoors in which the insects played an important role in the mPMI estimation are presented. The bodies of socially isolated people and old people living alone were discovered in central Italy between June and November. mPMI ranged from a few days to several weeks. Insects were collected during the body recovery and the postmortem. Climatic data were obtained from the closest meteorological stations and from measurements performed on the site. Sarcophagidae and Calliphoridae species were present in 75% of the cases with Lucilia sericata and Chrysomya albiceps collected in 50% of the cases. Chrysomya albiceps was always found in association with Lucilia species. Scuttle flies (Phoridae) were found in 37.5% of the cases, confirming the ability of these species in indoor body colonization. We show that if sealed environment may delay, the insect arrival dirty houses may create the environment where sarcosaprophagous insects are already present.     

Determination of Nitrite in Whole Blood by High‐Performance Liquid Chromatography with Electrochemical Detection and a Case of Nitrite Poisoning

Although nitrite is widely used in meat processing, it is a major toxicity hazard to children and is responsible for the blue‐baby syndrome. A simple and effective method to determine nitrite in whole blood has been devised using ion chromatography with suppressed conductivity detection. The blood sample was deproteinized by adding acetonitrile and purified with mini‐cartridges to remove hydrophobic compounds, chloride ions, and metal ions. An aliquot of the filtrate was injected onto the ion chromatography. The retention time for nitrite was 13.8 min and the detection limit of nitrite in whole blood was 0.4 μmol/L. The calibration curve was linear (r² = 0.9999) over the concentration working range. The blood nitrite concentration of a victim who attempted suicide by ingesting sodium nitrite powder was determined using the present method. The basal levels for nitrite in human blood was determined with 7.1 ± 0.9 μmol/L (n = 12).     

Assessment of post-mortem submersion interval using total aquatic decomposition scores of drowned human cadavers

Investigating drowning-related deaths remains a significant problem for forensic personnel all over the world. The previously published decomposition scoring method like the total aquatic decomposition (TAD) score promises to estimate the correct post-mortem submersion interval (PMSI) in aquatic habitats through the assessment and calculation of the decomposition rate and accumulated degree days (ADD). The current study comprised of 53 drowned death cases belonging to various districts of Haryana from May 2016 to August 2017. The regression and Pearson's correlation indicated a significant correlation between the TAD scores and the actual ADD (calculated through water temperatures) (r² = 0.917) and between the actual and the estimated ADDs (calculated through TAD scores used by Heaton et al. [21]) (r = 0.9585). The results indicated that the estimated ADD tends to over predict the PMSI compared to the actual ADD. It is further confirmed by paired t-test, which showed the mean of actual ADD (mean = 349) to be significantly lower than the mean of estimated ADD (mean = 663). Moreover, these methods will help forensic investigators and researchers formulate region-specific regression equations for PMSI estimation.     

Estimating Time Since Death from Postmortem Human Gut Microbial Communities

Postmortem succession of human‐associated microbial communities (“human microbiome”) has been suggested as a possible method for estimating postmortem interval (PMI) for forensic analyses. Here we evaluate human gut bacterial populations to determine quantifiable, time‐dependent changes postmortem. Gut microflora were repeatedly sampled from the proximal large intestine of 12 deceased human individuals as they decayed under environmental conditions. Three intestinal bacterial genera were quantified by quantitative PCR (qPCR) using group‐specific primers targeting 16S rRNA genes. Bacteroides and Lactobacillus relative abundances declined exponentially with increasing PMI at rates of N_t = 0.977e^?0.0144t (r² = 0.537, p < 0.001) and N_t = 0.019e^?0.0087t (r² = 0.396, p < 0.001), respectively, where N_t is relative abundance at time (t) in cumulative degree hours. Bifidobacterium relative abundances did not change significantly: N_t = 0.003e^?0.002t (r² = 0.033, p = 0.284). Therefore, Bacteroides and Lactobacillus abundances could be used as quantitative indicators of PMI.     

The Heritability of Palatal Rugae Morphology Among Siblings*†

Although there is clinical applicability of the palatal rugae as an identification tool in forensic odontology, controversy exists whether the palatal rugae patterns are stable or variable. The greater the genetic component, the higher the probability that palatal rugae patterns are stable. The aim of this study was to compare the palatal rugae morphology between full siblings and the proportion of variability due to genetic component. This cross-sectional study was conducted on digital models of 162 siblings aged 15–30 years old. The palatal rugae patterns were assessed with Thomas and Kotze (1983) classification using Geomagic Studio software (3D Systems, Rock Hill, SC). The palatal rugae morphology between siblings showed significantly similar characteristics for total number of left rugae (p = 0.001), left primary rugae (p = 0.017), secondary rugae for right (p = 0.024) and left sides (p = 0.001), right straight rugae (p = 0.010), and right convergent rugae (p = 0.005) accounting for at least 6.25%-12.8% of the variability due to heredity. Despite the similarities found, the palatal rugae patterns showed significant differences between siblings of at least 46.9% (p = 0.001). Zero heritability was found in 9 of the 14 rugae patterns. Meanwhile, total number of rugae, primary, backward, and convergent rugae showed moderate heritability (h² > 0.3) and total number of secondary rugae showed high heritability (h² > 0.6). In conclusion, despite the individuality characteristics, an appreciable hereditary component is observed with significant similarities found between sibling pairs and the palatal rugae patterns were both environmentally and genetically influenced.     

The Effects of Racemization Rate for Age Estimation of Pink Teeth

Pink teeth is thought to result from the seepage of hemoglobin caused by dental pulp decomposition. We investigated whether racemization can be applied for age estimation in cases of pink teeth where the whole tooth is used. The pink teeth used were three cases and the normal teeth for control were five mandibular canines of known age. Age of the pink teeth was calculated on the basis of regression formula obtained from the five control teeth. Only a slight error was noted between the actual and estimated ages of the pink teeth (R² = 0.980, r = 0.990): Cases 1–3 actually aged 23, 53, and 59 years were estimated to be 26, 52, and 60 years. Based on our results of testing pink teeth of known age, we suggest that racemization techniques allow for the age estimation of pink teeth using the same methods for normally colored teeth.     

A Reliable Regression‐Based Approach for Reassociating Human Skeletal Elements of the Lower Limbs from Commingled Assemblages

Accurate sorting of commingled human remains comprises a fundamental requirement for all further anthropological analyses. The lower limb bones are particularly important for reconstructing biological profiles. This study introduces a metric technique for sorting these elements using eight standard anthropological measurements and 222 adult individuals from Greece. The bones utilized were the os coxae, the femora, the tibiae and the tali. Simple regression analyses were used to develop functions for reassociating articulating bones, providing strong correlations (r = 0.74–0.95, p‐value <0.05) and high coefficients of determination (r²=0.54–0.91). Blind tests demonstrated that combining metric and morphoscopic techniques provides an excellent sorting accuracy for the hip and knee joints (ten of ten individuals), allowing for a reliable reassociation between a sex and age indicator (os coxae) and a body size indicator (femur). Overall, these results indicate the high value of metric methods in sorting commingled human remains.     

The Role of Vitreous Magnesium Quantification in Estimating the Postmortem Interval

The use of magnesium as a parameter to estimate the time of death is controversial. In 32 traumatic deaths with known postmortem intervals (PMIs), small quantities of vitreous humor (VH) were sampled repetitively every 3 h until 24 h postmortem. The bodies were kept at the constant ambient temperature of 20°C (68°F). The concentrations of magnesium were in the range of 0.47–1.15 mM. A statistically significant correlation of the concentration of magnesium with the PMI was observed (r = 0.453, p < 0.01), but with small predictive value—coefficient of variation for regression was 45.5%; the average of the paired differences between the estimated and actual PMIs was 5.24 + 3.19 h. Although useful results might be expected due to the large transmembrane gradient for magnesium, the results of this study strongly disprove the usefulness of measuring magnesium in VH to estimate the time of death.     

Temperature‐Dependent Postmortem Changes in Human Cardiac Troponin‐T (cTnT): An Approach in Estimation of Time Since Death

Estimation of time of death is an indispensible requirement of every medico‐legal autopsy, but unfortunately, there is not a single method by which it could be determined accurately. This study focused on the temperature‐dependent postmortem degradation of cardiac troponin‐T and its association with postmortem interval (PMI) in human. The analysis involved extraction of the protein, separation by denaturing gel electrophoresis (SDS‐PAGE), and visualization by Western blot using cTnT‐specific monoclonal antibodies. The area of the bands within a lane was quantified by scanning and digitizing the image using Gel Doc (Universal Hood). The results indicate a characteristic banding pattern among human cadavers (n = 6) and a pseudo‐linear relationship between percentage of cTnT degradation and the log of the time since death (r > 0.95), which can be used to estimate the postmortem interval. The data presented demonstrate that this technique can provide an extended time range during which PMI can be more accurately estimated.     

Establishing Correspondence in Wood: The Challenge and Some Solutions?

Establishing correspondence between the upper portion of a white birch sapling, a suspected weapon, and a potential source from a stand of trees was posed to one of us (GMC). A bending force shattered the sapling, precluding physical matching. Three white birch saplings were taken from the same stand of trees in a similar manner. Correspondence was achieved by measuring the width of the annual rings along four radii from a disk cut above and below the break. The regression coefficient of the data from the two disks from the same sapling was r² = 0.95. Regressing the upper disk against the lower disk of two other saplings resulted in r² values of 0.26 and 0.17, respectively. The various characteristics that are confined to a wood stem as part of its normal process of growth can be used to eliminate candidate saplings and establish correspondence between two pieces of wood.     

An Improved Equation for TBS and ADD: Establishing a Reliable Postmortem Interval Framework for Casework and Experimental Studies

Megyesi et al.'s (J Forensic Sci, 2005, 50, 618) paper was important to forensic anthropology as it introduced a quantitative framework for estimating time since death in human cadavers, based upon physical appearance by way of scoring on a novel scale. However, errors concerning rounding, temperature scale, and incorrect use of a statistical regression model render their predictive formula unusable. Based upon only their more reliable data, a more appropriate regression model to predict accumulated degree days (ADD) from total body score (TBS) is presented. The new model is also a superior fit (r² = 0.91) and produces markedly narrower confidence intervals than the original, which also allowed impossible, negative ADD values. Explanations of the shortcomings in the original analysis and calculations are presented, which it is hoped will help forensic scientists avoid making similar mistakes.     

Nonmetric Cranial Trait Variation and Ancestry Estimation in Asian and Asian-Derived Groups

Traditionally, precontact Native Americans and Asian groups have been conflated for aspects of the biological profile due to their distantly shared genetic history, although this grouping remains largely unexplored. This study examines craniomorphic variability to ascertain whether Asian groups can be differentiated from each other and from Asian-derived groups using more fine-tuned models. Cranial and mandibular data for 35 nonmetric traits were recorded on precontact Native Americans (n = 150) and modern Japanese (n = 150) and Thai (n = 150) individuals. Chi-square analyses indicate that all groups exhibit statistically significant differences in most traits. Additionally, cross-validated binary logistic regression equations resulted in correct classification rates in the range of 65.0–93.3% and demonstrate that sex does not contribute to statistical models. Therefore, numerous traits provide discriminatory resolution that detects differences between the samples, thus highlighting the potential utility of nonmetric traits in identifying individuals beyond the traditional African, European, and Asian forensic ancestry groupings.     

A Direct Aqueous Derivatization GSMS Method for Determining Benzoylecgonine Concentrations in Human Urine

A sensitive and reliable method for extraction and quantification of benzoylecgonine (BZE) and cocaine (COC) in urine is presented. Propyl‐chloroformate was used as derivatizing agent, and it was directly added to the urine sample: the propyl derivative and COC were then recovered by liquid–liquid extraction procedure. Gas chromatography–mass spectrometry was used to detect the analytes in selected ion monitoring mode. The method proved to be precise for BZE and COC both in term of intraday and interday analysis, with a coefficient of variation (CV) <6%. Limits of detection (LOD) were 2.7 ng/mL for BZE and 1.4 ng/mL for COC. The calibration curve showed a linear relationship for BZE and COC (r² >0.999 and >0.997, respectively) within the range investigated. The method, applied to thirty authentic samples, showed to be very simple, fast, and reliable, so it can be easily applied in routine analysis for the quantification of BZE and COC in urine samples.     

Bone Mineral Density Adult Age Estimation in Forensic Anthropology: A Test of the DXAGE Application

Estimating age‐at‐death of individuals represented only by skeletonized human remains is a fundamental aspect of forensic anthropological casework. Recently, several researchers have proposed that bone mineral density (BMD) is a useful predictor of age‐at‐death in forensic contexts. Navega et al. (JFS 63(2):497–503) developed an online application called DXAGE for calculating age‐at‐death from BMD parameters. This study tests the utility of DXAGE by utilizing data from the National Health and Nutrition Examination Survey (NHANES). BMD data from a female subsample (n = 470) of the NHANES 2007–2008 dataset were analyzed, and the relationship between predicted age and real age was examined. Inaccuracy was 14.25 years, and bias was ?7.20 years. Results show that there is a weak correlation between predicted and actual age (r = 0.47) using the DXAGE application. While BMD data are potentially useful for predicting age age‐at‐death, the DXAGE application should be used cautiously in forensic anthropological contexts.     

Forensic Dental Age Estimation by Measuring Root Dentin Translucency Area Using a New Digital Technique

Dentin translucency measurement is an easy yet relatively accurate approach to postmortem age estimation. Translucency area represents a two‐dimensional change and may reflect age variations better than length. Manually measuring area is challenging and this paper proposes a new digital method using commercially available computer hardware and software. Area and length were measured on 100 tooth sections (age range, 19–82 years) of 250 μm thickness. Regression analysis revealed lower standard error of estimate and higher correlation with age for length than for area (R = 0.62 vs. 0.60). However, test of regression formulae on a control sample (n = 33, 21–85 years) showed smaller mean absolute difference (8.3 vs. 8.8 years) and greater frequency of smaller errors (73% vs. 67% age estimates ≤ ±10 years) for area than for length. These suggest that digital area measurements of root translucency may be used as an alternative to length in forensic age estimation.     

Stature Estimation from Various Foot Dimensions Among Slovak Population

The foot measurements are important in forensic field as they can be used as body height predictors for an individual. The morphology of human feet shows the variations and therefore the aim of this study was to find the relation between stature and foot measurements and to generate population‐specific equations. We measured the stature and bilateral foot measurements of 71 volunteers ranging in age between 18 and 27 years using standard measurements technique. The results revealed nonsignificant bilateral differences in all sex groups (p < 0.05). Sex differences were found to be significant in all foot measurements (p < 0.001). The highest significant and positive correlation coefficients with stature were observed for foot length in males (r = 0.759), in females (r = 0.722), and in the sex‐mixed group (r = 0.865). According to the nonsignificant sex effects on the relation between stature and foot dimensions, the regression equations were computed only for the pooled mixed‐sex group. Our study provides equations that can help to estimate stature from foot measurements among Slovaks.