Effects of Decomposition on Gunshot Wound Characteristics: Under Moderate Temperatures with Insect Activity

Abstract:  Previous studies document characteristics of gunshot wounds shortly after they were inflicted. This study was conducted to determine if the early stages of decomposition obscure or alter the physical surface characteristics of gunshot wounds, thereby affecting the quantity and quality of information retrievable from such evidence. The study was conducted in August and September, 2005 in Nova Scotia, Canada in forested and exposed environments. Recently killed pigs were used as research models and were shot six times each at three different ranges (contact, 2.5 cm, and 1.5 m). Under these test conditions, the gunshot wounds maintained the characteristics unique to each gunshot range and changes that occurred during decomposition were not critical to the interpretation of the evidence. It was concluded that changes due to decomposition under the conditions tested would not affect the collection and interpretation of gunshot wound evidence until the skin was degraded in the late active or advanced decay stage of decomposition.     

Macroscopic,Microscopic, and Chemical Assessment of Gunshot Lesions on Decomposed Pig Skin

Abstract: Very little literature exists on gunshot wounds on decomposed material. In this study, seven pig heads underwent a shooting test. Entrance wounds from the first head underwent neutron activation analysis (NAA) and histological testing immediately after the firing test; the other six heads were exposed to two different environments (open air and soil) and analyzed by radiochemical and histological tests every 15 days. Gunshot wounds in air maintained their morphological characteristics, and those in soil showed severe alteration after 5 weeks. Microscopic testing verified positive results for lead in all gunshot wounds in open air, whereas in most of those in soil lead could not be detected. Radiochemical analysis performed by NAA yielded for all gunshot wounds but one antimony quantities in the range of 0.07–13.89 μg. In conclusion, it may be possible to detect residues of antimony even in degraded tissues.     

Gunshot residues on dry bone after decomposition-a pilot study

Abstract: Very little literature exists concerning radiochemical and microscopic analyses of gunshot wounds in decomposed material, and even less concerning skeletonized samples; the most advanced technologies may provide useful indications for the diagnosis of suspect lesions, especially if gunshot wounds are no longer recognizable. However, we know very little of the survival of gunshot residues (GSR) in skeletonized samples. This study examined nine gunshot wounds produced on pig heads which then underwent skeletonization for 4 years, and four gunshot entries on human heads from judicial cases which were then macerated to the bone in water; the samples underwent scanning electron microscopy coupled with energy dispersive X‐ray (SEM‐EDX) analysis. Positive results for GSR were observed only in four of the nine animal samples and in all four human samples. Among the human samples, two lesions showed Pb and Sb, one lesion only Pb, and one Pb, Sb, and Ba. This pilot study showed the survival of GSR in skeletal material and therefore the crucial importance of SEM‐EDX analyses on skeletonized material. Further studies are needed in order to ascertain the role of environmental modifications of GSR.     

Detection of Gunshot Primer Residue on Bone in an Experimental Setting—An Unexpected Finding*

Abstract: Pork ribs with intact muscle tissue were used in an experimental attempt to identify bullet wipe on bone at distances from 1 to 6 feet with 0.45 caliber, full metal jacket ammunition. This resulted in the unexpected finding of primer‐derived gunshot residue (GSR) deep within the wound tract. Of significance is the fact that the GSR was deposited on the bone, under the periosteum, after the bullet passed through a Ziploc^® bag and c. 1 inch of muscle tissue. It is also important to note that the GSR persisted on the bone after the periosteum was forcibly removed. The presence of primer‐derived GSR on bone provides the potential to differentiate gunshot trauma from blunt trauma when the bone presents an atypical gunshot wound. In this study, the presence of gunshot primer residue at a distance of 6 feet demonstrates the potential for establishing maximum gun‐to‐target distance for remote shootings.     

92式手枪射入口形态特征与射击距离的关系

目的研究手枪射入口形态特征与射击距离的关系,为射击距离的推断提供依据。方法选择92式手枪,在带皮的猪肉上覆盖白色棉布,设计了0m,0.1m,0.2m,0.5m1.0m,1.5m,3.0m,5.0m,10m,15.0m,20.0m,25.0m共12个射击距离,对白棉布和肉皮上的弹孔进行拍照,对比研究不同射击距离的射入口形态特征,并利用Autocad软件对射入口的面积进行计算。结果白棉布和肉皮上射入口的形态特征与射击距离有一定的相关性。结论根据射入口的形态特征,能够对射击距离进行推断,对涉枪案件中射击距离的判断有参考价值。     

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.     

Differentiation of bullet type based on the analysis of gunshot residue using inductively coupled plasma mass spectrometry

Porcine tissue samples shot with two different types of bullets, jacketed and nonjacketed, were collected in the fresh state and throughout moderate decomposition. Wound samples were microwave-digested and analyzed using inductively coupled plasma mass spectrometry (ICP-MS) to detect all elements present at measurable levels in gunshot residue (GSR). Elements detected included antimony (Sb), barium (Ba), and lead (Pb), which are considered characteristic of GSR, as well as iron (Fe) and copper (Cu). These five elements were used to differentiate shot tissue and unshot tissue, as well as tissue shot by the two different bullet types, both in the fresh state and throughout moderate decomposition. The concentrations of Cu, Sb, and Pb were able to distinguish the two bullet types in fresh tissue samples at the 95% confidence level. Cu and Pb were able to differentiate the bullet types throughout moderate decomposition at the 99% confidence level.     

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.     

Pseudo-Stab Wounds: Putrefactive Dehiscence of Remote Surgical Incisions Masquerading as Stab Wounds

Abstract:  Artifacts due to decomposition can be mistaken for antemortem injury leading to an incorrect suspicion of foul play. We describe an instance of postmortem wound dehiscence that mimicked antemortem stab wounds. A man with a history of colon cancer and substance abuse was found dead. There were advanced putrefactive changes and multiple defects of the anterior torso that resembled stab wounds. Subsequent investigation revealed that 11 months earlier, he had a laparoscopic-assisted colon resection that involved surgical incisions corresponding in location and size to the above defects. Putrefactive gases may cause bloating of the body. This distension may cause recent and remote healed incisions to dehisce. Correlation of these defects at autopsy with the antemortem clinical history is crucial in determining their etiology.     

A method for enhancing gunshot residue patterns on dark and multicolored fabrics compared with the modified Griess test

In using infrared or infrared-enhanced photography to examine gunshot residue (GSR) on dark-colored clothing, the GSR particles are microscopically examined directly on the fabric followed by the modified Griess test (MGT) for nitrites. In conducting the MGT, the GSR is transferred to treated photographic paper for visualization. A positive reaction yields an orange color on specially treated photographic paper. The examiner also evaluates the size of the powder pattern based on the distribution of nitrite reaction sites or density. A false-positive reaction can occur using the MGT due to contaminants or dyes that produce an orange cloud reaction as well. A method for enhancing visualization of the pattern produced by burned and partially unburned powder is by treatment of the fabric with a solution of sodium hypochlorite. In order to evaluate the results of sodium hypochlorite treatment for GSR visualization, the MGT was used as a reference pattern. Enhancing GSR patterns on dark or multicolored clothing was performed by treating the fabric with an application of 5.25% solution of sodium hypochlorite. Bleaching the dyes in the fabric enhances visualization of the GSR pattern by eliminating the background color. Some dyes are not affected by sodium hypochlorite; therefore, bleaching may not enhance the GSR patterns in some fabrics. Sodium hypochlorite provides the investigator with a method for enhancing GSR patterns directly on the fabric. However, this study is not intended to act as a substitute for the MGT or Sodium Rhodizonate test.     

Debugging Decomposition Data—Comparative Taphonomic Studies and the Influence of Insects and Carcass Size on Decomposition Rate

Abstract:  Comparison of data from a variety of environments and ambient temperatures has previously been difficult as few studies used standardized measures of time/temperature and decomposition. In this paper, data from previous studies and recent experiments are compared using simple conversions. These conversions allow comparison across multiple environments and experiments for the first time. Plotting decomposition score against logADD allows the exponential progression of decomposition to be expressed as a simple linear equation. Data comparison from many environments and temperatures shows no difference in decomposition progression when measured using Accumulated Degree Days. The major effector of change in rate was insect presence, regardless of depositional environment, species, or season. Body size is significant when carcasses are accessed by insects; when insects are excluded, while bodies are indoors, submerged, or buried, then decomposition progresses at the same rate regardless of body size.     

The Effects of Soil Environment on Postmortem Interval: A Macroscopic Analysis

Abstract:  Burial environment, in particular soil moisture, has a significant impact on the type, rate, and extent of bone degradation, which ultimately affects estimations of the postmortem interval (PMI). The purpose of this research is to determine the effects of soil moisture on the color, weight, condition, and texture of bone as it relates to the PMI. Bone changes occurring over two different time intervals (2 and 5 months) were examined using 120 sus scrofa leg bones. During each time interval bones were buried in two soil environments, one of which was drier than the other. The bones in both environments lost weight over time but the net weight loss was greater for bones in the higher moisture environment. There was no change in color, texture, or overall condition, indicating that 150 days is not long enough for such alterations to occur, regardless of the moisture level of the burial environment.     

The Influence of Insects on Decomposition Rate in Buried and Surface Remains

Abstract: This article reports results of a comparative study of decomposition rates of wild rabbit (Oryctolagus cuniculus) which were either (i) buried after exposure to insect activity, (ii) buried without exposure, (iii) kept above ground behind an insect screen, or (iv) continuously exposed above ground in a field experiment. Results showed that dipteran oviposition occurred consistently in groups i and iv only. Decomposition rates (measured by Total Body Score every c. 50 accumulated degree days [ADD]) of rabbits kept behind the screen and those buried without exposure showed no difference (p = 0.450). This was significantly slower than those buried after exposure (p = 0.0016) which was in turn significantly slower than those continuously exposed (p << 0.001). Temperatures collected from animals showed the presence of feeding larvae increased intra‐abdominal temperatures to >5°C above ambient. The findings support the assertion that insect presence is the primary agent affecting decomposition rate via tissue consumption and also the heat they generate.     

A versatile technique for the investigation of gunshot residue patterns on fabrics and other surfaces: m-XRF

With heavy-metal-free ammunitions becoming more and more popular, it is necessary to find methods to visualize patterns of those elements in gunshot residues (GSRs) that are not accessible by chemographic coloring tests. The recently introduced millimeter-X-ray fluorescence analysis (m-XRF) spectrometer Spectro Midex M offers an easy way to record mappings of GSRs containing such elements in order to determine shooting distances as well as the general composition of these particles. A motorized stage enables samples of a maximum size of 20 x 20 cm to be investigated, like fabric, clothes, adhesive tapes (Filmolux films), and polyvinylalcohol gloves of shooter's hands. Human tissues can be measured using a Peltier-cooled specimen holder that is mounted onto the stage. As the spot size of the exiting X-rays lies in the millimeter range, which is adequate for the assessment of the residue patterns for shooting distance determination, a significant reduction in measurement time is achieved compared with mu-XRF methods. Test shots with heavy-metal-free ammunitions were performed on different target materials, like pork skin and fabric, and the elemental distributions of Ti, K, and Ga were determined. In order to show the capability of the spectrometer for conventional lead ammunitions as well, a shot series of 5-100 cm shooting distance and an adhesive tape of a shooter's hand were investigated analogously. A comparison of several methods applied in GSR investigation shows the advantages of the m-XRF method.     

Forensic identification science evidence since Daubert: Part II--judicial reasoning in decisions to exclude forensic identification evidence on grounds of reliability

Many studies regarding the legal status of forensic science have relied on the U.S. Supreme Court's mandate in Daubert v. Merrell Dow Pharmaceuticals Inc., and its progeny in order to make subsequent recommendations or rebuttals. This paper focuses on a more pragmatic approach to analyzing forensic science's immediate deficiencies by considering a qualitative analysis of actual judicial reasoning where forensic identification evidence has been excluded on reliability grounds since the Daubert precedent. Reliance on general acceptance is becoming insufficient as proof of the admissibility of forensic evidence. The citation of unfounded statistics, error rates and certainties, a failure to document the analytical process or follow standardized procedures, and the existence of observe bias represent some of the concerns that have lead to the exclusion or limitation of forensic identification evidence. Analysis of these reasons may serve to refocus forensic practitioners' testimony, resources, and research toward rectifying shortfalls in these areas.     

Diesel fumes do kill: a case of fatal carbon monoxide poisoning directly attributed to diesel fuel exhaust with a 10-year retrospective case and literature review*

While it is known that diesel fuel combustion engines produce much lower concentrations of carbon monoxide (CO) than gasoline engines, these emissions could certainly generate lethal ambient concentrations given a sufficient amount of time in an enclosed space and under suitable environmental conditions. The authors report a case of CO poisoning which was initially referred for autopsy as a presumed natural death of a truck driver found in the secure cab of a running diesel tractor trailer truck. Completion of the preliminary investigation ascribed death to complications of ischemic heart disease (IHD), pending toxicological analysis that included quantification of CO. When the toxicology results showed lethal blood COHbg, the cause of death was re-certified as CO intoxication secondary to inhalation of (diesel) vehicular exhaust fumes. Because of the unique source of fatal CO intoxication in this case, the contributory IHD and the possible contaminants in the putrefied blood, a 10-year retrospective review was conducted on all nonfire related CO deaths autopsied (n = 94) at the Office of the Chief Medical Examiner in Louisville, KY from 1994 to 2003. For validation of the COHbg detection method used by the Kentucky Office of Forensic Toxicology (KYOFT), blood samples from these cases along with controls were submitted to three laboratories using various analytical methods yielding no statistically significant differences. Lastly, an extensive literature review produced no scientifically reported cases of fatal CO poisoning attributed to diesel fuel exhaust.     

Advantage of affinity histochemistry combined with histology to investigate death causes: indications from sample cases

Mast cell histochemistry has been proposed in addition to classic histological methods to estimate the course of traumatic events before and after death. We have addressed the utility of this approach on nine victims of different types of trauma. Sections of wounded skin were stained with hematoxylin and eosin and with fluorescent avidin to tag mast cells. Mast cell numbers were evaluated by both direct and digitalized counts. Intact skin was used as control. The results on mast cells implemented the findings upon hematoxylin and eosin stain and helped to put the wounds and death in chronological sequence. Digitalized morphometry allowed to reduce intra- and inter-observer variation. We conclude that combined histological and histochemical analyses can be of practical use in forensic pathology, that a preliminary setting of the reference values is needed for each laboratory, and that image analysis can be of help for the quantification of the results.     

Pulse Variations of a Conducted Energy Weapon (Similar to the TASER® X26 Device): Effects on Muscle Contraction and Threshold for Ventricular Fibrillation*

Abstract: Conducted energy weapons (such as the Advanced TASER X26 model produced by TASER International), incapacitate individuals by causing muscle contractions. To provide information relevant to development of future potential devices, a “Modifiable Electronic Stimulator” was used to evaluate the effects of changing various parameters of the stimulating pulse. Muscle contraction was affected by pulse power, net/gross charge, pulse duration, and pulse repetition frequency. The contraction force increased linearly as each of these factors was increased. Elimination of a precursor pulse from X26‐like pulses did not have a significant effect on the normalized force measured. Muscle‐contraction force increased as the spacing increased from 5 to 20 cm, with no further change in force above 20 cm of spacing. Therefore, it is suggested that any future developments of new conducted energy weapons should include placement of electrodes a minimum of 20 cm apart so that efficiency of the system is not degraded. In the current study, the 50% probability of fibrillation level of X26‐like pulses ranged from 4 to 5 times higher than the X26 itself. Relatively large variations about the X26 operating level were found not to result in fibrillation or asystole. Therefore, it should be possible to design and build an X26‐type device that operates efficiently at levels higher than the X26.     

Detection of Acute Diazepam Exposure in Bone and Marrow: Influence of Tissue Type and the Dose‐Death Interval on Sensitivity of Detection by ELISA with Liquid Chromatography Tandem Mass Spectrometry Confirmation*

Abstract: Enzyme‐linked immunosorbent assay (ELISA) and liquid chromatography tandem mass spectrometry (LC/MS/MS) were used to detect diazepam exposure in skeletal tissues of rats (n = 15) given diazepam acutely (20 mg/kg, i.p.), and killed at various times postdose. Marrow, epiphyseal, and diaphyseal bone were isolated from extracted femora. Bone was cleaned, ground, and incubated in methanol. Marrow underwent ultrasonic homogenization. Extracts and homogenates were diluted in phosphate buffer, and then underwent solid‐phase extraction and ELISA. Relative sensitivity of detection was examined in terms of relative decrease in absorbance (ELISA) and binary classification sensitivity (ELISA and LC/MS/MS). Overall, the data showed differences in relative sensitivity of detection of diazepam exposure in different tissue types (marrow > epiphyseal bone > diaphyseal bone), which is suggestive of heterogenous distribution in these tissues, and a decreasing sensitivity with increasing dose‐death interval. Thus, the tissue type sampled and dose‐death interval may contribute to the probability of detection of diazepam exposure in skeletal tissues.