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.     

Postmortem Measurement of Human Chorionic Gonadotropin in Vitreous Humor and Bile

Abstract: Postmortem human chorionic gonadotrophin (HCG) blood assay can confirm postmortem diagnosis of pregnancy or document situations in which HCG levels are elevated. In some cases, however, blood sampling is not possible at autopsy. In this study, HCG was quantified by enzyme‐linked fluorescent assay (ELFA) in the bile (n = 5), vitreous humor (n = 4), and postmortem blood (n = 4) of five pregnant women. There were no false negatives in the pregnant subjects (n = 5) or false positives in controls (n = 34), enabling this test to be recommended for routine use in forensic contexts in which the detection of elevated HCG levels could be of interest.     

The Etiology of Basal Vacuolizations in Renal Tubular Epithelial Cells Evaluated in an Isolated Perfused Kidney Model

To determine whether basal lipid vacuolization characteristic of ketoacidosis could be induced with short‐term hypertriglyceridemia, adult Sprague Dawley rat kidneys were perfused in an isolated perfused kidney model with, and without, 11.3 mM (10 g/L) of triglycerides in Krebs‐Henseleit buffer, for 1 and 2 h (n = 5/group). Additional treatments included perfusion with triglycerides with 20 mM of β‐hydroxybutyrate and 2 mM of acetoacetate (n = 5) and perfusion with triglycerides with 70 mM of glucose (n = 1). Basal vacuolization was produced in all groups, but differed in morphology to that reported in postmortem studies. There was no further increase in vacuolization after 2 h of perfusion compared to 1 h (p = 0.24), and the addition of ketones did not alter the morphology or extent of vacuolization. This study using an ex vivo model has confirmed that isolated hypertriglyceridemia is sufficient to cause basal lipid vacuolization in renal tubular epithelial cells, but with different morphology to vacuoles observed in lethal ketoacidosis at autopsy.     

Using Frons Width to Differentiate Blow Fly Species (Diptera: Calliphoridae) Phormia regina (Meigen) and Protophormia terraenovae (Robineau‐Desvoidy)

Protophormia terraenovae (Robineau‐Desvoidy) (Diptera: Calliphoridae) and Phormia regina (Meigen) (Diptera: Calliphoridae) are morphologically similar blow fly species commonly used for estimating postmortem intervals. Field collection and storage of adults can result in color changes, in particular on calypters and palps; often collected specimens show damage such as wing fray or fungal growth. We measured the frons width: total head width ratio using photographs (ImageJ version 1.49) to differentiate these two species. Both sexes were distinguishable to species, with the greatest difference between males: 12.34% P. terraenovae versus 1.62% P. regina, less so for females: 40.25% P. terraenovae, versus 33.65% P. regina. Incorporating this feature into future blow fly keys would help with distinguishing field‐caught specimens when other features are obstructed.     

Comprehensive evaluation of pericardial biochemical markers in death investigation

Pericardial fluid (PCF) is a well-preserved cadaveric material in cases without structural damage. The present study investigated fundamental serum components of PCF, including total proteins (TP), albumin (Alb), urea nitrogen (UN), creatinine (Cr), uric acid (UA), glucose (Glu), sodium (Na), potassium (K), chloride (Cl), calcium (Ca) and magnesium (Mg) in PCF with regard to the postmortem and survival periods, and cause of death in serial medicolegal autopsy cases (n = 288) with intact pericardial and cardiac structures within 48 h postmortem. The amount of PCF (mostly 5–25 ml) showed no survival or postmortem time dependence, or difference among the causes of death. For all cases, there were moderate postmortem decreases of Na and Cl, and increases of K and Mg, which were insufficient for application to estimate the time since death; however, characteristic findings with regard to the cause of death were detected in cases of hours-long survival, especially in ‘functional causes of death’: higher Alb, UN, Cr, UA, K and Mg, and lower Na, Cl and Ca in intoxication; lower TP, Alb, Cr, K and Mg, and higher Na and Cl in hypothermia (cold exposure); higher Alb, UN, Cr, UA and Mg, and lower Glu and Ca in hyperthermia (heatstroke). These observations suggest the usefulness of pericardial biomarkers for investigating the cause and process of death to reinforce pathological and toxicological findings.     

Evaluation of Postmortem Cerebrospinal Fluid S100B Protein and Serotonin Levels: Comparison of Suicidal Versus Nonsuicidal Deaths in Konya,Turkey

Although suicide is a preventable public health problem, objective assays for suicide risk are limited. In this study, it was aimed to determine levels of S100B protein and serotonin as a marker for risk of suicide. S100B protein and serotonin levels were investigated with ELISA method in the cerebrospinal fluid (CSF) in medicolegal autopsy cases, including those of suicide cases (n = 32) and nonsuicide cases (n = 56). The CSF S100B levels were higher (9.3 ± 2.9 ng/mL vs. 5.4 ± 2.0 ng/mL), and serotonin levels were lower (10.4 ± 4.9 ng/mL vs. 19.0 ± 5.7 ng/mL) in suicide group than nonsuicide group (p < 0.05). There was no correlation between S100B protein and serotonin levels with gender, age groups, postmortem interval, and cause of death. It is concluded that both S100B protein and serotonin in CSF may be useful for determination of suicide risk.     

Artifacts Caused by Leaf-Cutting Ants of the Genus Atta (Hymenoptera: Formicidae): Postmortem Bite Injuries and the Tearing of Clothes

Ants are one of the first insects to find an exposed cadaver and can be present during all stages of decomposition. Although these organisms are not commonly used in postmortem interval estimates, they are to be taken into account on criminal investigations involving human corpses, since they can leave bite marks that can be mistaken for antemortem or perimortem injuries, which could be misleading when ascertaining the occurrence of abuse or physical altercation during a crime. A few studies report the action of ants on human cadavers and even though leaf-cutting ants of the genus Atta are frequently encountered in succession studies that use animal carcasses, there are no records of these fungus-growing species on human corpses. Atta is a genus restricted to the New World, ranging from northern Argentina to southern United States and acts as one of the most conspicuous neotropical herbivores. In this study, we report three cases of violent death that illustrate the impact of ants, especially those of the genus Atta, in a forensic setting. We compare the patterns displayed by postmortem bite injuries caused by leaf-cutter ants and other common species with less robust mandibles. We also present the capability of Atta ants to create artifacts by cutting victim’s clothes in a crime scene, contributing to the knowledge of ant-mediated confounding factors in crime scene investigation.     

Bacterial Translocation and Sample Contamination in Postmortem Microbiological Analyses

The diagnostic value of postmortem bacteriology has been discussed controversially for decades. In the study herein, contamination during sampling procedures and postmortem translocation were investigated to interpret postmortem microbiology results. One hundred medicolegal autopsy cases in total were included. Radiology, histology, bacteriology, and biochemistry were performed in all cases. Based on all investigation findings, 4 groups of cases were identified: death unrelated to infection, true infections, false positive (contamination during sampling procedures, postmortem translocation and mixed situations), and undetermined. The results of this study indicate that postmortem bacteriology provides useful data supporting infection‐related deaths, especially when potentially significant observations are accompanied by consistent autopsy, histology, and biochemistry. Result interpretation requires careful evaluation of number and type of isolated microorganisms.     

The Interest of Postmortem Bacteriology in Putrefied Bodies

A 27‐year‐old man was found dead in an advanced decomposition stage at home. On external examination, his body showed petechial hemorrhages of the skin. At autopsy, petechial hemorrhages of the epicardium were found, but no sign of meningitis was detected. Toxicological investigations remained negative. Bacteriological conventional analyses showed no significant result. Neisseria meningitidis serogroup B was finally isolated on cerebrospinal fluid by a specific real‐time polymerase chain reaction. To our knowledge, there are no available data about the postmortem diagnosis of an infectious cause of death in a decomposed corpse. In such situations, the polymicrobial overgrowth usually hampers the interpretation of bacteriological conventional methods and questions their diagnostic value. Such molecular bacteriological approaches appear to constitute an important diagnostic tool for forensic scientists and should be widely processed in case of suspected infectious death or sudden death whatever the postmortem interval.     

The Effect of Flunitrazepam (Rohypnol®) on the Development of Chrysomya megacephala (Fabricius, 1794) (Diptera: Calliphoridae) and its Implications for Forensic Entomology

This study investigated the potential effects of flunitrazepam (known as “date rape drug”) on the developmental cycle of Chrysomya megacephala, an important forensic species, and their possible implications for the calculation of the PMI. A 1050 C. megacephala eggs were divided into five groups with seven replications each. The eggs were placed on artificial diet prepared with four drug concentrations of flunitrazepam (4, 8, 16, and 32 ng/g), besides the control group (prepared with water). Were evaluated the potential effects on development time, weight gain, and mortality during the cycles. The drug had no significant effect on development time or mortality although it did affect the weight of the pupae and adults (Kruskal–Wallis, p < 0.05). The result can be deduced that the determination of the postmortem interval is not affected.     

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.     

Postmortem Serum Tryptase Levels with Special Regard to Acute Cardiac Deaths

An elevated serum tryptase concentration is considered a specific marker for systemic mast cell activation, a central feature of anaphylaxis. However, in some cases of acute cardiovascular death, high concentrations of serum tryptase are also observed. We compared the postmortem serum tryptase concentrations in 74 cases assigned to the following four groups: anaphylactic deaths (Group A, n = 20), acute cardiac deaths (Group ACD, n = 30), acute dissecting aneurysm ruptures (Group ADA, n = 10), and controls (Group C, n = 14). Additionally, the cutoff between Group A and the other groups was calculated using receiver‐operating characteristic (ROC) curve analysis. Tryptase concentrations were markedly elevated in Group A (p < 0.001), Group ACD (p = 0.015), and Group ADA (p = 0.005). The optimal cutoff was 43 ng/mL, the sensitivity was 90%, and the specificity was 98%. While elevated concentrations of tryptase were noted in practical autopsy cases, due attention should be paid to the differential diagnosis between anaphylactic and acute cardiovascular deaths.     

Postmortem Blood Concentrations of R‐ and S‐Enantiomers of Methadone and EDDP in Drug Users: Influence of Co‐Medication and P‐glycoprotein Genotype

Abstract: We investigated toxicological and pharmacogenetic factors that could influence methadone toxicity using postmortem samples. R‐ and S‐methadone were measured in femoral blood from 90 postmortem cases, mainly drug users. The R‐enantiomer concentrations significantly exceeded that of the S‐enantiomers (Wilcoxon’s test, p < 0.001). The samples were divided into four groups according to other drugs detected (methadone only, methadone and strong analgesics, methadone and benzodiazepines, or methadone and other drugs). There was no significant difference in any of the R‐methadone/total methadone ratios among the four groups. The median R/S ratio was 1.38, which tends to be higher than that reported for the plasma of living subjects. In addition, we investigated whether small nucleotide polymorphisms in the MDR1 gene that encode the drug transporter P‐glycoprotein were associated with the concentrations of R‐ and S‐methadone and its metabolite 2‐ethylidene‐1,5‐dimethyl‐3,3‐diphenylpyrrolidine. No significant association was detected.     

Sex‐ and Size‐Related Patterns of Carrion Visitation in Necrodes littoralis (Coleoptera: Silphidae) and Creophilus maxillosus (Coleoptera: Staphylinidae)

The estimation of postmortem interval (PMI) based on successional patterns of adult insects is largely limited, due to the lack of potential PMI markers. Sex and size of adult insects could be easily used for such estimation. In this study, sex‐ and size‐related patterns of carrion attendance by adult insects were analyzed in Necrodes littoralis (Coleoptera: Silphidae) and Creophilus maxillosus (Coleoptera: Staphylinidae). For both species, abundance of males and females changed similarly during decomposition. A slightly female‐biased sex ratio was recorded in N. littoralis. Females of N. littoralis started visiting carcasses, on average, one day earlier than males. There was a rise in size of males of N. littoralis at the end of decomposition, whereas for females of both species and males of C. maxillosus, no size‐related patterns of carrion visitation were found. Current results demonstrate that size and sex of adult carrion beetles are poor indicators of PMI.     

Measurement of Postmortem Pupil Size: A New Method with Excellent Reliability and Its Application to Pupil Changes in the Early Postmortem Period

Measurement of postmortem pupil width is a potential component of death time estimation. However, no standardized measurement method has been described. We analyzed a total of 71 digital images for pupil–iris ratio using the software ImageJ. Images were analyzed three times by four different examiners. In addition, serial images from 10 cases were taken between 2 and 50 h postmortem to detect spontaneous pupil changes. Intra‐ and inter‐rater reliability of the method was excellent (ICC > 0.95). The method is observer independent and yields consistent results, and images can be digitally stored and re‐evaluated. The method seems highly eligible for forensic and scientific purposes. While statistical analysis of spontaneous pupil changes revealed a significant polynomial of quartic degree for postmortem time (p = 0.001), an obvious pattern was not detected. These results do not indicate suitability of spontaneous pupil changes for forensic death time estimation, as formerly suggested.     

Volatile Organic Compound Profiling from Postmortem Microbes using Gas Chromatography–Mass Spectrometry

Volatile organic compounds (VOCs) are by-products of cadaveric decomposition and are responsible for the odor associated with decomposing remains. The direct link between VOC production and individual postmortem microbes has not been well characterized experimentally. The purpose of this study was to profile VOCs released from three postmortem bacterial isolates (Bacillus subtilis, Ignatzschineria indica, I. ureiclastica) using solid-phase microextraction arrow (SPME Arrow) and gas chromatography–mass spectrometry (GC-MS). Species were inoculated in headspace vials on Standard Nutrient Agar and monitored over 5 days at 24°C. Each species exhibited a different VOC profile that included common decomposition VOCs. VOCs exhibited upward or downward temporal trends over time. Ignatzschineria indica produced a large amount of dimethyldisulfide. Other compounds of interest included alcohols, aldehydes, aromatics, and ketones. This provides foundational data to link decomposition odor with specific postmortem microbes to improve understanding of underlying mechanisms for decomposition VOC production.     

“Bath Salts” the New York City Medical Examiner Experience: A 3‐Year Retrospective Review

“Bath salts” are synthetic derivatives of cathinones, compounds found in the leaves of Catha edulis, which possesses amphetamine‐like properties. At the New York City Office of Chief Medical Examiner, we conducted a 3‐year retrospective analysis of deaths in which cathinones were detected. Two categories emerged; those in which cathinones were a contributory cause of death (15 cases) and those in which they were an incidental finding (15 cases). Of the former group, 13 were associated with additional intoxicants; two deaths were attributed solely to cathinone intoxication, both survived 10 h: a man whose postmortem blood methylone concentration was 0.71 mg/L and a woman whose postmortem blood ethylone concentration was 1.7 mg/L. In the latter category, there were several individuals who had higher concentrations of cathinones than the above two, the highest being a blood methylone of 4.8 mg/L. Based upon our data and the literature presented, lethal concentrations of cathinones cannot be established.     

Arthropods of Forensic Importance on Pig Carrion in the Coahuilan Semidesert,Mexico

Abstract: This is the first report of an ongoing research to establish a sarcosaprophagous arthropod database in the Coahuilan semidesert. Seven pigs (Sus scrofa L.) were used as human models to determine succession in an open urban area during the 2007 winter–spring period. Arthropods were collected manually and from pitfall traps. Carcass biomass loss, as well as arthropod colonization, was recorded during 71 days postmortem. Five decomposition stages were identified during which most abundant orders were found to be Diptera, Coleoptera, and Hymenoptera. Lucilia sericata (Meigen), Chrysomya rufifacies (Macquart), Necrobia rufipes (DeGeer), Dermestes maculatus (DeGeer), Pheidole hyatti Emery, and Pogonomyrmex rugosus Emery stood out as dominant species.     

The Influence of Penetrative Trauma on the Rate of Decomposition*†

Abstract: An understanding of the factors affecting decomposition is important for the accurate estimation of postmortem interval. An experimental study on the influence of penetrating trauma on decomposition rate was carried out using the domestic pig, Sus scrofa. The results of this study were: (i) Diptera were preferentially attracted to and oviposited at natural orifices. Trauma sites were not preferentially selected for oviposition; (ii) no differences between trauma and non‐trauma groups were found in time to skeletonization, weight loss (p = 0.906), total body score (p = 0.824), body temperature (p = 0.967), or changes in soil pH (p = 0.684); and (iii) the effect of investigator disturbance was significant when decomposition was measured as weight loss (p = 0.000). This study suggests that penetrating trauma of the type used in this study cannot be considered a major factor in the rate of decomposition and time to skeletonization of a gunshot trauma victim.