Does a Draft Really Influence Postmortem Body Cooling?*

Estimation of the time of death (TOD) is a very important task of forensic pathologist, and measurement of body temperature is a method deemed to be most precise during the initial postmortem period. The study aimed at verification of the significance of airflow present in the room where a corpse is found on body cooling process and hence on determination of the TOD. The experiment was performed in pigs during which the postmortem temperature of the eye, muscles, and rectum was recorded--in still air and with generated draft in the room. The results showed that the moderate airflow present in the experimental conditions did not significantly affect the course of cooling of the investigated body sites. Despite moderate wind generated in the room, the air movement close to pigs' bodies was actually minimal. This allowed to conclude that to evaluate the TOD most precisely, one should first have reliable data on the actual velocity of air in the direct vicinity of the body rather than relying on subjective sensation of the draft and using various unnecessary corrective coefficients for TOD calculation.     

Comparison of patterns of decomposition in a hanging carcass and a carcass in contact with soil in a xerophytic habitat on the Island of Oahu, Hawaii

Decomposition studies were conducted to determine differences in rates and patterns of decomposition of carcasses hanging and exposed on the surface of the soil. These studies were conducted between 17 October and 17 December 1997 inside of Diamond Head Crater on the island of Oahu, Hawaii. The animal model was the domestic pig. Sus scrofa. The rate of biomass removal from the hanging carcass was significantly slower than that observed for the control carcass during the bloat and decay stages of decomposition. Internal temperatures for the control carcass were elevated above the ambient air temperatures during the earlier stages of decomposition (bloated and decay), while those recorded for the hanging carcass approximated the ambient air temperatures. There was a greater diversity of arthropod species recorded and numbers of individuals observed were higher for the control carcass. A significant site of arthropod activity was observed on the surface of the soil immediately under the hanging carcass and this became the primary site of arthropod activity as decomposition progressed.     

Rectal temperature time of death nomogram: sudden change of ambient temperature

Cooling experiments on dummies known as body-like cooling were performed with sudden decrease and increase of ambient temperature in the order of 15 degrees C. In the case of a sudden decrease of ambient temperature, a second 'temperature plateau' occurs which is shorter than the known plateau at the beginning of body cooling. The cooling curves can be described mathematically by a three-step procedure based on the two-exponential term of the 'nomogram method'. The second plateau at the beginning of the second cooling phase in sudden decreased ambient temperature requires a lower value of the constant A (1.15) compared with the known value (1.25) at the beginning of body cooling. In the case of a sudden increase of ambient temperature in the order of 15 degrees C no procedure could be found to model the cooling curves mathematically.     

Effect of carcass size on rate of decomposition and arthropod succession patterns.

Decomposition studies were conducted using two carcasses of domestic pigs, Sus scrofa L., 8.4 kg and 15.1 kg in weight, to determine the effects of carcass size on the rate of decomposition, composition of the arthropod fauna, and succession patterns. A total of 46 arthropod taxa were recovered during this study. No size-related differences were observed between carcasses with respect to composition of the arthropod fauna or patterns of succession. A greater number of arthropods were observed attracted to the 15.1-kg carcass, and the rate of decomposition observed was more rapid for the 15.1-kg carcass than for the 8.4-kg carcass. Internal temperatures of the 8.4-kg carcass were more directly related to external ambient temperatures during the fresh and bloated stages of decomposition. During the decay stage, both carcasses generated internal temperatures significantly above ambient temperatures. Following this stage, internal temperatures fell to approximate ambient temperatures during the postdecay and remains stages.     

Experimental and casework validation of ambient temperature corrections in forensic entomology

This paper expands on Archer (J Forensic Sci 49, 2004, 553), examining additional factors affecting ambient temperature correction of weather station data in forensic entomology. Sixteen hypothetical body discovery sites (BDSs) in Victoria and New South Wales (Australia), both in autumn and in summer, were compared to test whether the accuracy of correlation was affected by (i) length of correlation period; (ii) distance between BDS and weather station; and (iii) periodicity of ambient temperature measurements. The accuracy of correlations in data sets from real Victorian and NSW forensic entomology cases was also examined. Correlations increased weather data accuracy in all experiments, but significant differences in accuracy were found only between periodicity treatments. We found that a >5°C difference between average values of body in situ and correlation period weather station data was predictive of correlations that decreased the accuracy of ambient temperatures estimated using correlation. Practitioners should inspect their weather data sets for such differences.     

Sex identification of white-tailed deer using frozen venison

Fluids from frozen muscle tissue taken from 449 white-tailed deer (Odocoileus virginianus) were analyzed using a radioimmunoassay technique for testosterone. Comparing 309 deer sampled in early November, antlered males had significantly higher tissue testosterone levels (range = 0.18 to 16.00 ng/mL) than females (range = 0.00 to 0.18 ng/mL) while antlerless (fawn) males overlapped both groups (range = 0.00 to 0.68 ng/mL). Samples taken from 132 deer from January through August showed no differences among ages or sexes. Antlered males can be differentiated from females during the breeding season.     

Estimating the Time of Death in Domestic Canines

Abstract:  Because 36.1% of U.S. households have dogs, the time of death (TOD) of dogs at crime scenes can be useful to forensic investigators. However, there are few published studies based on postmortem changes in dogs. This study, conducted indoors in still air at approximately room temperature, monitored the postmortem reduction in rectal, liver, brain, and aural temperatures in 16 dogs for 32 h after death. Graphs of temperature reduction were prepared to estimate the TOD of dogs within the first 32 h postmortem. Sex, body mass, and hair coat density did not affect the rate of body temperature reduction, but increased body weight and volume slowed it. Rectal temperature was the most convenient, reasonable site for measuring body temperature. Vitreous humor potassium ion concentration [K⁺] was measured in both eyes at c.  1.5 and 7 h after death. Both eyes had the same [K⁺] when measured simultaneously, and [K⁺] increased after death.     

A Nonlinear Least Squares Approach to Time of Death Estimation Via Body Cooling

The problem of time of death (TOD) estimation by body cooling is revisited by proposing a nonlinear least squares approach that takes as input a series of temperature readings only. Using a reformulation of the Marshall–Hoare double exponential formula and a technique for reducing the dimension of the state space, an error function that depends on the two cooling rates is constructed, with the aim of minimizing this function. Standard nonlinear optimization methods that are used to minimize the bivariate error function require an initial guess for these unknown rates. Hence, a systematic procedure based on the given temperature data is also proposed to determine an initial estimate for the rates. Then, an explicit formula for the TOD is given. Results of numerical simulations using both theoretical and experimental data are presented, both yielding reasonable estimates. The proposed procedure does not require knowledge of the temperature at death nor the body mass. In fact, the method allows the estimation of the temperature at death once the cooling rates and the TOD have been calculated. The procedure requires at least three temperature readings, although more measured readings could improve the estimates. With the aid of computerized recording and thermocouple detectors, temperature readings spaced 10–15 min apart, for example, can be taken. The formulas can be straightforwardly programmed and installed on a hand‐held device for field use.     

Insect succession and decomposition patterns on shaded and sunlit carrion in Saskatchewan in three different seasons

A study was conducted on decomposition and insect succession in the Prairie Ecozone of Saskatchewan in the year 2000. Eighteen domestic pig carcasses (42-79 kg) were employed as human models for applications to future homicide investigations in this region. Two major variables were considered including the effect of season and habitat (sun versus shade). Research was conducted over 25 weeks, spanning three seasons: spring, summer and fall. Ambient temperature, internal carcass temperature, faunistic succession over time, and the rate of decay were all compared for each experimental variable. Results indicated that habitat was only a factor in the decompositional rate of carrion in the spring season. The ambient temperature was the chief factor determining the seasonal variations in decay rate. Maximum internal carcass temperatures always coincided with the presence of 3rd instar larvae. Patterns of insect succession occurred in a predictable sequence that varied across different habitats and seasons and was unique compared to previously published studies. Carcasses placed in spring and fall attracted a more diverse assemblage of insects than summer-placed carrion. Sun-exposed carrion also had greater variation in fauna than shaded carrion in spring and fall. Members of Silphidae were the first coleopteran colonizers in all habitats and seasons. This paper also marks the first record for Cochliomyia macellaria (Fabricius) in Saskatchewan.     

Effect of Investigator Disturbance in Experimental Forensic Entomology: Carcass Biomass Loss and Temperature

Abstract: Often carrion decomposition studies are conducted using a single carcass or a few carcasses sampled repeatedly through time to reveal trends in succession community composition. Measurements of biomass and other abiotic parameters (e.g., temperature) are often collected on the same carcasses but are rarely a focal point of the studies. This study investigated the effects that repeated sampling during experiments have on the decomposition of carrion, measured as both gross biomass (carcass plus fauna) and net biomass (carcass only), on carcasses disturbed on every visit (with weighing only or also with the collection of fauna) and on carcasses disturbed only once. Each trial lasted at least 21 days, with samples taken in triplicate. Rat carcasses used in this study were placed in the field on the same day and either weighed on every visit or ignored until a given day. Internal and ambient air temperatures were recorded on each carcass at the time of sampling and on undisturbed carcasses using temperature loggers. The presence of succession fauna did not result in significant biomass loss on most days; however, there were individual days early in decomposition (days 3 through 6) when the succession fauna comprised a large portion of the gross biomass. With the exception of biomass loss by the emigration of maggots on days 4 and 5, neither repeated weighing of the carcasses nor repeated weighing and faunal sampling of the carcasses statistically affected the rate of biomass loss. Internal temperatures of carcasses sampled repeatedly were frequently 2–5°C lower than those that had not been disturbed, and ambient temperatures differed significantly depending on the location of measurement device. Results indicate that methods used historically for biomass loss determination in experimental forensic entomology studies are adequate, but further refinements to experimental methodology are desirable.     

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.     

A Preliminary Examination of Differential Decomposition Patterns in Mass Graves

Five pairs of mass graves, each containing carcasses of 21 rabbits, were used to examine differential decomposition at four locations within the burial: surface, deep, mid‐outer, and core. Every 100 accumulated degree days (ADD), a pair of graves was exhumed, and total body score (TBS) and internal carcass temperature of each rabbit were recorded. Decomposition did not differ for core‐ and deep‐positioned carcasses (p = 0.13); differences were significant (p < 0.001) for all other location comparisons. Decomposition occurred fastest in shallow carcasses, followed by mid‐outer carcasses; deep and core carcasses decomposed slowest and at rates not significantly different from one another. Adipocere formation was minimal and confined to deep carcasses. Carcass location within the mass grave significantly influenced internal carcass temperature (p < 0.001); a mean internal temperature difference of ca. 1°C existed between deep and shallow carcasses (30 cm apart). Effects of mass compactness and oxygenation require further investigation.     

Canid modification of human remains: implications for time-since-death estimations

Time-since-death estimations are usually based on physical decomposition of the corpse, insect succession, and contextual associations. The rates of change and succession are based on decomposition studies, most of which control access of scavengers to the corpse; however, many naturally exposed corpses are subject to scavenger modification. These modifications change the rate of decomposition, the pattern of insect succession, and the context of associations, thus altering estimations of time since death. A controlled feeding study with captive wolves and road-killed deer is pertinent to understanding canid scavenging and how scavenging may alter postmortem changes. During feeding, the wolves commonly dismember and devour the deer in a predictable sequence. Although there are some variations in the usual sequence, the carcass is always moved, and skeletal elements are separated, diminished in size and scattered. Scavenging must, therefore, be considered in estimating time since death.     

A model for the aging of fly larvae in forensic entomology

A method is described for determining the time of hatching of blowfly larvae on a corpse with respect to temperature. Temperature is known to have a profound effect on the rate of growth of fly larvae, and it is suggested that past assumptions that the growth of larvae found in a corpse has taken place at one approximated ambient temperature may have led to large overestimates of the development time of the larvae, and thus overestimates of time of death. Larvae of Lucilia cuprina, Calliphora vicina (= erythrocephala), Calliphora stygia and Calliphora hilli were cultured under constant temperatures, and their growth rates modeled with a logistic growth curve. Two programmes have been developed, one to compute the parameters for the logistic equations, the other is used to estimate the time elapsed from the time at which a sample is removed from a body to the estimated hatching time of the larvae comprising the sample, with temperatures and species as variables.     

First practical applications of eye temperature measurements for estimation of the time of death in casework. Report of three cases

This paper presents first three successive cases of death where at scene measurements of the internal eyeball temperature soon after death allowed to precisely estimate the times of deaths based on this data (33.1°C, 32.2°C and 29.5°C, respectively), which were later confirmed during the police investigation. Simultaneously the rectal temperatures in all three cases were measured and appeared to be between 36.3 and 36.8°C-reflecting a living individual's body temperature. Thanks to a significantly faster postmortem decrease of the eye temperature and a residual or nonexistent plateau effect affecting the eye, using the formula developed in previous comprehensive studies in pigs, the time of death in real cases could be estimated with good precision: 1 h 33 min, 2 h 24 min and 3 h 17 min since death respectively. The actual TOD established during investigation appeared to be: between 1 h 30 min and 1 h 50 min in case 1; 1 h 55 min in case 2 and between 2 h 55 min and 3 h 05 min in case 3. Such precise estimation, mainly due to the plateau effect lasting up to a few hours, could not have been done based only on rectal temperature, commonly measured in forensic practice.     

Carrion fly (Diptera: Calliphoridae) larval colonization of sunlit and shaded pig carcasses in West Virginia, USA

Two pig (Sus scrofta L.) carcasses were placed in sunlit and shaded plots in September 2003, and again in May 2004. Mean ambient temperatures between sunlit and shaded plots were not significantly different in either September or May, but mean ambient temperatures at sunlit and shaded plots in 2004 were significantly higher than corresponding means for sunlit and shaded plots in 2003. Mean maggot mass temperatures were significantly higher than ambient plot temperatures for all four experimental plots (i.e., sunlit and shaded carcasses in both 2003 and 2004). In addition, maggot mass temperatures on sunlit carcasses were positively, and significantly, correlated with ambient temperatures, whereas there was no significant correlation between maggot mass and ambient temperatures at shaded plots. Carcass decomposition proceeded more rapidly in 2004 in the presence of higher ambient temperatures, and sunlit carcasses decomposed faster than shaded ones in both 2003 and 2004 experiments. Phaenecia coeruleiviridis (Macquart) and Phormia regina (Meigen) third instars dominated collections on all four carcasses, but there was little temporal overlap between these species with third instars of the former dominating collections in the early portion (approximately 40%) of each experimental period (with the exception of the shaded carcass in 2004 where both species were co-dominant), and the latter assuming dominance in the latter portion (approximately 60%). Lower accumulated degree hour values were calculated for instar development on 2004 carcasses subjected to higher ambient temperatures.     

Messenger RNA profiling: a novel method for body fluid identification by real-time PCR

Conventional methods for the identification of different body fluids like blood, semen and saliva from biological stains involve immunological or enzymatic detection of certain proteins. In this study, we investigated potential RNA markers with the aim of developing Real-Time polymerase chain reaction (PCR) based methods to allow differentiation between several body fluids. Total RNA samples from artificially stained swabs and from various pieces of evidence from case work were extracted, amplified and analyzed with several RNA markers. Three assays detecting the body fluids of interest were selected: hemoglobin-alpha locus 1 (HBA), kallikrein 3 (KLK) and mucin 4 (MUC). With this approach, we demonstrate that specific Real-Time PCR assays are useful in identifying the source of the biological stain. Furthermore, RNA profiling of various body fluids was even possible on samples stored over a long period of time at ambient temperature. The stability and sensitivity of the applied method outlines a novel application for Real-Time PCR within the forensic field.     

Effect of storage conditions on restriction fragment length polymorphism (RFLP) analysis of deoxyribonucleic acid (DNA) bound to positively charged nylon membranes.

The ability to generate an autoradiogram from deoxyribonucleic acid (DNA) immobilized on a positively charged nylon membrane could be compromised by the storage conditions of the membrane. HaeIII-digested human DNA was size fractionated and transferred to two types of positively charged nylon membranes. The membranes were stored at -20 degrees C, 4 degrees C, and ambient temperature and humidity for times ranging from 1 day to 13 weeks, then hybridized to variable number of tandem repeat (VNTR) probes to examine the effect of the storage conditions on the membrane-bound DNAs. It was shown that such membranes could be successfully hybridized and rehybridized if they were stored at -20 or 4 degrees C, but storage under ambient conditions reduced or eliminated the likelihood of successful hybridization.     

Sustained combustion of an animal carcass and its implications for the consumption of human bodies in fires

When a human body is found with significant portions of its torso and limbs destroyed yet with comparatively minor damage to head, hands and feet, the mechanism of such destruction defies ready explanation, since exposure to external fires, particularly those involving flammable liquids, usually results in the destruction of hands, feet, limbs, and head prior to significant combustion of the large mass of the torso. Previous tests by these authors have demonstrated the conditions necessary to promote combustion of a body: the presence of adequate body fat, presence of a porous, rigid char to act as a wick, and an external flame source sustained for several minutes to char the body and cause the subcutaneous fat to begin rendering. In the test reported here, a freshly-slaughtered pig carcass with a net weight of 215 lb. (95 kg) was wrapped in a cotton blanket and placed on a carpet-covered plywood panel. The fire was initiated using 1 L of gasoline poured on the shoulder area of the blanket-wrapped carcass. The gasoline burned off within 4 min, having ignited a large area of the blanket and adjoining carpet. Flames from those fuel packages resulted in the establishment of a steady-state fire sustained by the rendering of the body fat, with the necessary wick provided by the charred cotton blanket and carpet. The heat release rate of this fire was 60+/-10 kW, with flames less than 12 in. (0.35 m) high for its duration. The fire sustained itself by the rendering process for more than 6 1/2 h from ignition, at which time it was extinguished. An average mass loss rate of 1.5 g/s (5.3 kg/h) was observed during the self-sustained fire. Extensive destruction of the carcass (more than 60% by weight) included reduction of large bones to a fragile, ashen state. Other test data will demonstrate the similarity between subcutaneous fat from human and porcine sources. The implications for the reconstruction of accidental and homicidal fires involving such destruction will be discussed.     

Seasonal Variation of Carcass Decomposition and Gravesoil Chemistry in a Cold (Dfa) Climate

It is well known that temperature significantly affects corpse decomposition. Yet relatively few taphonomy studies investigate the effects of seasonality on decomposition. Here, we propose the use of the Köppen‐Geiger climate classification system and describe the decomposition of swine (Sus scrofa domesticus) carcasses during the summer and winter near Lincoln, Nebraska, USA. Decomposition was scored, and gravesoil chemistry (total carbon, total nitrogen, ninhydrin‐reactive nitrogen, ammonium, nitrate, and soil pH) was assessed. Gross carcass decomposition in summer was three to seven times greater than in winter. Initial significant changes in gravesoil chemistry occurred following approximately 320 accumulated degree days, regardless of season. Furthermore, significant (p < 0.05) correlations were observed between ammonium and pH (positive correlation) and between nitrate and pH (negative correlation). We hope that future decomposition studies employ the Köppen‐Geiger climate classification system to understand the seasonality of corpse decomposition, to validate taphonomic methods, and to facilitate cross‐climate comparisons of carcass decomposition.