Disaster victim identification: new applications for postmortem computed tomography

Abstract:  Mass fatalities can present the forensic anthropologist and forensic pathologist with a different set of challenges to those presented by a single fatality. To date radiography has played an important role in the disaster victim identification (DVI) process. The aim of this paper is to highlight the benefits of applying computed tomography (CT) technology to the DVI process. The paper begins by reviewing the extent to which sophisticated imaging techniques, specifically CT, have been increasingly used to assist in the analysis of deceased individuals. A small scale case study is then presented which describes aspects of the DVI process following a recent Australian aviation disaster involving two individuals. Having grided the scene of the disaster, a total of 41 bags of heavily disrupted human remains were collected. A postmortem examination was subsequently undertaken. Analysis of the CT images of all body parts ( n  = 162) made it possible not only to identify and side differentially preserved skeletal elements which were anatomically unrecognizable in the heavily disrupted body masses, but also to observe and record useful identifying features such as surgical implants. In this case the role of the forensic anthropologist and CT technology were paramount in facilitating a quick identification, and subsequently, an effective and timely reconciliation, of body parts. Although this case study is small scale, it illustrates the enormous potential for CT imaging to complement the existing DVI process.     

A study of drug detection in a postmortem pediatric population

At The Office of the Cuyahoga County Coroner (CCCO), Cleveland, Ohio, it is customary to perform an autopsy and conduct toxicological testing on decedents less than 19 years of age. This study provides a retrospective evaluation of drugs detected in a pediatric postmortem population between the years 1998 and 2002 (n = 730). Demographic information, cause and manner of death, and toxicological results were examined. Blacks comprised 54% of cases, males 59%, and 48% were less than one year of age or stillborn. Forty-two percent of deaths were ruled natural, 27% accident, 13% undetermined, 5% suicide, and 2% homicide. Of the 640 cases subjected to comprehensive testing, 38% of the cases were positive for at least one compound. Resuscitative/treatment drugs were detected most frequently (56% of positive results), followed by illicit drugs (26%), ethanol (11%), carbon monoxide (8%), and antihistamines (6%). Eighty-seven cases contained more than one drug. The deaths of 47 individuals were drug related (6%). In this population, it is recommended that illicit drugs and ethanol are targeted for testing, especially when limited specimens are available for analysis.     

Rodents as taphonomic agents: bone gnawing by brown rats and gray squirrels

Passive infrared technology was used to film diurnal and nocturnal scavenging behavior of brown rats and gray squirrels at the University of Tennessee's Anthropological Research Facility. This direct documentation demonstrated that brown rats modified fat-laden cancellous bone while gray squirrels generally gnawed the thicker bone cortices only after fats had leached away. A case study placed in a shaded portion of the Facility indicated the postmortem interval for initial gnawing by gray squirrels was slightly over 30 months. An examination of 53 human skeletons in the William M. Bass Forensic Skeletal Collection revealed that 10 cases had gnaw marks consistent with those made by gray squirrels. One of the 10 cases had been gnawed within 16 months of time-since-death, while the remaining nine had postmortem intervals >30 months. Additional observed modifications made to nonhuman bone by gray squirrels indicate that squirrel gnaw marks on bone can serve as a minimal estimate of time-since-death in a temperate environment similar to that of East Tennessee.     

Estimating the timing of long bone fractures: correlation between the postmortem interval, bone moisture content, and blunt force trauma fracture characteristics*

There is very limited knowledge about how long perimortem fracture characteristics persist into the postmortem interval (PMI). Therefore, in this study, 60 porcine long bones were exposed to natural taphonomic conditions and fractured with a steel bone breaking apparatus every 28 days throughout a 141-day period. Differences between macroscopic blunt force trauma fracture characteristics (fracture angle, surface morphology, and outline) were examined to determine if they varied over time or in relationship to bone moisture content (ash weight) and overall assessment. There are significant relationships between (1) PMI and percent ash weight (%AW), fracture surface, and fracture angle and (2) %AW and fracture surface and fracture angle. Bone moisture content correlates significantly with fracture morphology and other characteristics commonly used by forensic anthropologists to determine the timing of traumatic injuries. However, fracture characteristics normally associated with perimortem trauma can persist long into the PMI.     

Fentanyl concentrations in 23 postmortem cases from the hennepin county medical examiner's office

The purpose of this study was to compare blood fentanyl concentrations in fentanyl-related deaths with fentanyl concentrations found incidentally at autopsy, as well as with fentanyl concentrations found in hospitalized patients receiving fentanyl. Between the years 1997 to 2005, 23 fentanyl-positive postmortem cases were identified. Nineteen of 23 (82.6%) cases were deemed to be drug overdoses. Fentanyl alone was responsible for 8 of the 19 (42.1%) overdose deaths. Mean and median fentanyl concentrations were 36 (SD 38) microg/L and 22 microg/L, respectively, range 5-120 microg/L. Seven of the cases were accidental, one undetermined. The remaining 11 of the 19 (57.9%) cases were mixed drug overdoses. Fentanyl concentrations in these cases were 31 (SD 46) microg/L, range 5-152 microg/L. All of the mixed drug overdoses were determined to be accidental. Four cases where fentanyl was considered an incidental postmortem finding were determined to be natural deaths. In hospitalized inpatients (n = 11) receiving fentanyl 2 of the patients receiving fentanyl for chronic pain for more than 3 months had concentrations of 8.5 microg/L and 9.9 microg/L. The other nine inpatient concentrations were less than 4 microg/L. In conclusion, blood fentanyl concentrations found in cases where fentanyl alone was determined to be the cause of death were similar to cases where fentanyl was part of a mixed drug overdose. There was also considerable overlap between fentanyl concentrations in fentanyl-related overdose deaths compared to hospitalized patients being treated for chronic pain. Fentanyl concentrations in postmortem cases must be interpreted in the context of the deceased's past medical history and autopsy findings.     

The formation of early stage adipocere in submerged remains: a preliminary experimental study

In some circumstances, the presence of adipocere may retard decomposition and complicate postmortem interval estimation. This article explores the correlation between Accumulated Degree Days (ADD) and early stage formation of adipocere. Sixty wild rabbit (Oryctolagus cuniculus) carcasses were used in this experiment; a control group (N = 30) deposited directly on the ground surface and an experimental group (N = 30) completely submersed in water in individual buckets. Data (water and inner body temperature, pH, and total body score) were collected every 100 ADD. Results indicated that early stage adipocere is correlated to ADD and that its formation on submersed remains is more likely to occur after 630 ADD. Skin sloughing promoted the formation of adipocere. No adipocere was formed on any of the control group rabbits. This study also highlights the fact that multiple factors influence adipocere formation and it is suggested that further research needs to be conducted into this area.     

Caddisflies assist with homicide case: determining a postmortem submersion interval using aquatic insects

Although few indicators of time since death for corpses found in aquatic ecosystems are comparable in precision to the insect indicators used in terrestrial cases, there are observations that can be useful in suggesting or ruling out an approximate PMSI (postmortem submersion interval). For example, the time intervals required for certain growth phases of aquatic insects, such as caddisflies, that may attach themselves to the submerged remains can be used to estimate a minimum PMSI. Approximately 8 of the 13 orders of insects containing species with aquatic or semi-aquatic stages are likely to be associated with carrion or corpses in aquatic habitats. We present a case study in which portions of a body from an adult male were discovered in a south central Michigan stream. The body was dismembered and portions were recovered from two bags floating and submerged in the stream. Insect specimens collected from mesh and plastic bags consisted of one fly larva belonging to the family Muscidae, and caddisfly larvae belonging to two families: the Limnephilidae. (case-makers) and the Hydropsychidae, (net spinners). We used unique case-building behaviors of the limnephilid caddisflies found on the remains to elucidate a PMSI range consistent with the disappearance of the victim. It is important for forensic investigators to understand that although some precision is lost in estimating a PMSI with aquatic insects, these organisms should not be ignored in gathering evidence from aquatic crime scenes, and in fact, they can provide valuable details in estimating a PMSI.     

氯胺酮在家兔死后体内的弥散研究

目的研究氯胺酮在大白兔体内死后弥散过程和再分布机制。方法 48只实验大白兔随机分为8组,采用缺氧处死后以150mg/kg氯胺酮灌胃,尸体仰卧位于室温下放置;在0~96h内分8个时间点各解剖1组,提取体液和脏器组织样品;采用GC/MS法定性结合GC-NPD法定量检测样品中氯胺酮含量,并计算心血/外周血中氯胺酮含量的比值。结果大白兔死后氯胺酮灌胃尸体放置96h内,脑、尿液、玻璃体液、左上/下肢肌肉样本中均未检测到氯胺酮,心血、外周血、心肌、脾、肾、肝、肺、胆汁中氯胺酮含量随死后时间呈动态升高的变化;其中距离胃较近的组织(如脾)较早检测到含量较高的氯胺酮,而距离较远的组织或体液中氯胺酮含量较低且较晚检测到;心血/外周血中氯胺酮含量比值为1.73。结论氯胺酮在家兔体内存在死后再分布,从胃到器官组织、心血顺浓度梯度弥散是主要机制。脑、玻璃体液、尿液、肢体肌肉不受死后弥散的影响,可作为生前服毒与死后染毒氯胺酮的鉴别依据。     

脑血管造影在法医学尸体检验中的应用

脑血管造影作为诊断脑血管疾病的"金标准",目前已经广泛地应用于临床医疗活动中,并积累了丰富的理论和实践资料,是趋于成熟的技术方法。由于因脑血管疾病引发的法医学鉴定案件较为多见,故该技术近年开始应用于法医学,显示出在法医学实践中独特而重要的应用价值。本文对脑血管造影术在法医学中的应用价值进行综述,内容包括辅助定位血管病变或损伤部位、明确出血性质、指导尸体解剖与脑组织病理取材等,并在此基础上展望了该技术在法医学中的应用前景。     

Algor mortis: an erroneous measurement following postmortem refrigeration

Determination of the time of death is one goal of medicolegal death investigations. Algor mortis has been used as a measure of the postmortem interval (PMI). We prospectively recorded the core temperatures of 19 adult bodies entering our morgue cooler and at 3, 6, and 9 h of refrigeration. We then compared the cooling rate with the calculated body mass index (BMI). For each individual body, the rate of cooling was fairly linear with no evidence of a plateau. There was fair to moderate correlation between the BMI and the cooling rate: cooling rate = -0.052 (BMI) + 3.52. The probability of linearity in any given case was 36%. Variables affecting this correlation included the presence and the layers of clothing and if the clothing was wet. Our data confirm that algor mortis is of very limited utility in determining the PMI in bodies that have been refrigerated.     

Identification of the Edentulous Individual: An Investigation into the Accuracy of Radiographic Identifications*

Abstract: The dental identification of edentulous individuals can be challenging based on the lack of antemortem materials and unique features visible on radiographs. The constant resorption of the alveolar ridges further complicates the process. The purpose of this study was to quantify the error rate and reliability of dental identifications based on a comparison of synthesized antemortem and postmortem radiographs of edentulous individuals. Ten observers examined ten cases on two occasions and reported dichotomous and conclusion level decisions. These were analyzed using Kappa and Receiver Operator Characteristics. The mean area under the curve was 0.75 and the mean sensitivity was 0.57 and specificity was 0.83. These results suggest that dental identifications of edentulous individuals using radiographs alone have a high error rate and should be dual reported. These data add further weight to the argument that all dental prostheses should be labeled.     

Differential decomposition patterns in charred versus un-charred remains

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

根据肝脏死后改变推断死亡时间的研究进展

机体死后会发生一系列的改变,是腐败的过程,也是器官组织细胞自溶的过程。在司法实践中,通过研究肝脏死后改变,可以更准确的推断死亡时间,为案件的侦破提供线索。本文综述了近几十年来,利用肝脏死后变化推断死亡时间的研究进展。     

The influence of site of collection on postmortem morphine concentrations in heroin overdose victims

When assaying for postmortem morphine concentration, significant site sampling variability exists between central and peripheral sampling sites and even within sampling regions of the body. To study the variation, 76 suspected heroin overdoses were identified. Each had femoral artery (FA) and vein (FV), left and right ventricle and pooled heart blood samples obtained at autopsy. Forty-four tested positive for morphine. Morphine concentrations were determined by gas chromatography/mass spectrometry, with sampling site differences reported as log-transformed ratios and compared by signed rank test.The mean FA to FV ratio for total morphine was 1.2 (range 0-4.5). The ratio for left heart to right heart total morphine was 1.1 (range 0.4-3.2). Left ventricular to FV total morphine ratio was 2.0 (range 0.6-6.9). In these opioid overdose deaths, FA and FV morphine concentrations are usually similar, although up to 4.5-fold differences were noted. Centrally obtained morphine concentrations are on average twice as high compared with peripheral morphine concentrations. Left and right ventricular morphine concentrations were usually similar, although up to 3.2-fold differences were noted (left side higher).     

Prediction of eye color from genetic data using Bayesian approach

Prediction of visible traits from genetic data in certain forensic cases may provide important information that can speed up the process of investigation. Research that has been conducted on the genetics of pigmentation has revealed polymorphisms that explain a significant proportion of the variation observed in human iris color. Here, on the basis of genetic data for the six most relevant eye color predictors, two alternative Bayesian network model variants were developed and evaluated for their accuracy in prediction of eye color. The first model assumed eye color to be categorized into blue, brown, green, and hazel, while the second variant assumed a simplified classification with two states: light and dark. It was found that particularly high accuracy was obtained for the second model, and this proved that reliable differentiation between light and dark irises is possible based on analysis of six single nucleotide polymorphisms and a Bayesian procedure of evidence interpretation.     

The Teaching of Denture Marking Methods in Dental Schools in the United Kingdom and the United States*,†

Abstract: Forensic organizations worldwide have recommended that dental prostheses should be marked with, at a minimum, the patient’s name and preferably with further unique identifiers such as a social security number. The current study aimed to assess the denture marking practice of dental schools within the United States and the United Kingdom. A questionnaire‐based survey was employed to gain both quantitative and qualitative data on the methods, practices, and ethos behind denture marking in 14 U.K. and 32 U.S. dental schools. One hundred percent of U.K. and 87.5% of U.S. schools returned surveys and the results suggest that, for dental schools where there is no legal or legislative need for denture marking, the practice is inconsistently taught and appears to be reliant on internal forces within the school to increase awareness. Among those schools practicing marking, only 18% employ a technique likely to withstand common postmortem assaults; this is a concern.     

不同环境条件下大鼠死后皮肤大体和组织学改变

目的研究观察大鼠在不同环境条件下死后不同时间其皮肤大体、组织学的改变,为推测较长的死后间隔时间建立实验动物依据。方法观察雌性SD大鼠在不同环境条件下的死后变化,并间隔一定死后时间取皮、染色和镜下观察。结果死后发生骨、软组织分离,A组约需35d,B组需13d。皮肤有形细胞成分和附属器完全分解破坏,A组约20d,B组7d。胶原纤维在A组死后40d（B组12d）仍有部分保留完整。结论环境温度差异是造成A、B两组发生死后改变时程不同的主要因素,利用皮肤大体、组织学改变可望较系统和准确的推测晚期死亡时间。     

大鼠死后肌动蛋白降解与死亡时间的相关性

目的观察大鼠死后不同时间心肌、肝、脾、肺、肾、脑和骨骼肌肌动蛋白（actin）的降解规律,为晚期死亡时间（postmortem interval,PMI）的推断寻找客观指标。方法28只SD大鼠随机分为7组,经机械性窒息致死后．分别置于20℃恒温箱内,于0、24、48、72、96、120和168h后剖取以上器官,应用免疫印迹技术检测各组织内actin的含量,SPSS11．5软件对所得数据进行方差分析。结果大鼠死后上述各器官actin含量均随PMI的延长而逐渐下降,与PMI相关,决定系数（R2）均在0．75以上。但actin在上述各器官内的降解速度有显著差异（P〈O．05）,在脑组织中降解速度最快,其余依次为肺、脾、肝、肾、心肌和骨骼肌。结论尽管大鼠死后心肌、肝、脾、肺、肾、脑和骨骼肌actin的降解规律具有组织差异性,但是actin在上述组织中的含量变化与PMI相关．有助于较晚期PMI的推断。     

Free amino acid concentrations in vitreous humor and cerebrospinal fluid in relation to the cause of death and postmortem interval

We studied free amino acids in vitreous humor and cerebrospinal fluid from 58 cadavers in the course of routine medicolegal autopsies in the city of Granada. The main objective was to establish whether free amino acids contents in these fluids were related with the cause of death, postmortem interval, and severity of the classic signs of asphyxia. The amino acids (aspartic acid, glutamic acid, serine, glutamine, glycine/threonine/histidine, citruline, arginine, alanine, taurine, GABA, tirosine, valine, methionine, isoleucine, phenylalanine/tryptophan, leucine, and lysine) were quantified by high performance liquid chromatography. There were no statistically significant differences in amino acids concentrations in vitreous humor when the different causes of death were considered. Our results did not show any statistically significant relationship when asphyxial score was plotted against the vitreous content of each amino acid. A statistically significant increase with postmortem interval was observed in vitreous taurine (r = 0.3191, p = 0.01461), glutamate (r = 0.4323, p = 0.0007) and particularly in aspartate (r = 0.4508, p = 0.0003).