Multiple-probe thermography for estimating the postmortem interval: II. Practical versions of the Triple-Exponential Formulae (TEF) for estimating the time of death in the field

A simple, reliable, and relatively accurate method for estimating the time since death is described. It is based on the Triple-Exponential Formulae (TEF), which are devised for the first time in this study. The postmortem cooling rate of the brain, liver, and rectum in 117 forensic cases were investigated (Part I). The method can be used in the field as a computer program, reference graph, or reference chart-ruler. The program is simple and can easily be run by any user. There are six reference graphs representing the average brain, liver, and rectal cooling curves for naked and covered body groups. The ruler is designed for the rectal cooling curves for covered and naked bodies. This method requires one temperature measurement of the chosen body site and the environment. The postmortem interval is estimated as a probable value +/- a possible range of time estimates with a built-in confidence limit.     

Factors influencing the precision of estimating the postmortem interval using the triple-exponential formulae (TEF). Part I. A study of the effect of body variables and covering of the torso on the postmortem brain, liver and rectal cooling rates in 117 forensic cases

Brain, liver, rectal and environmental temperatures were continuously monitored under controlled conditions, in 117 forensic fatalities, for up to 60 h after death. Cases were studied either naked (63%) or covered with two blankets (37%). Bodies were classified into fat and thin groups. Statistical analysis and curve-fitting of the data yielded the average triple-exponential formulae for each body site and each body group. The effects of covering of the torso and body parameters such as weight, height, surface area and 'cooling size factor' (Z) on postmortem cooling are assessed and discussed. Results show that covering of the torso has a significant influence on the rate of postmortem cooling, however, there is no good correlation between the body variables and the cooling rate.     

Factors influencing the precision of estimating the postmortem interval using the triple-exponential formulae (TEF). Part II. A study of the effect of body temperature at the moment of death on the postmortem brain, liver and rectal cooling in 117 forensic cases

The temperatures of three body sites, namely, the brain, liver and the rectum as well as the temperature of the environment were continuously monitored, every 5-10 min, in 117 forensic cases commencing soon after death and in most cases, within 45 min postmortem. The body temperature at the moment of death was empirically determined by a computer-based extrapolation method. Thus, temperature data for the first 3h of each body site were fitted to single-exponential equations and the fitted curve was extrapolated backwards to obtain the intercept on the Y-axis (the temperature axis). The effect of body temperature at the moment of death on postmortem cooling rate is examined and factors influencing body temperature at death are discussed. Forensic fatalities associated with hyper and hypothermia are reviewed briefly.     

A statistical analysis of successional patterns in carrion-arthropod assemblages: implications for forensic entomology and determination of the postmortem interval.

A set of statistical protocols is proposed for analyzing carrion-arthropod succession in forensic entomology investigations. A total of 23 carrion-arthropod data sets from temperate, tropical, desert, and coastal environments were assembled in a standard format and analyzed using randomization tests and methods derived from quantitative community ecology. The data were analyzed in three ways. First, patterns of arthropod visitation on nonhuman carcasses were analyzed in each of the 23 cases. Analysis revealed two groups of taxa: those that persist on the carcass over a single time interval (= nonreoccurring taxa, 80% of the taxa) and those that appear, leave, and reappear over time on the carcass (= reoccurring taxa, 20%). Reoccurring taxa, which can confound estimation of the postmortem interval (PMI), were found in 6 classes, 12 orders, and 29 taxonomic families of arthropods, including some forensically important taxa (for example, calliphorids, sarcophagids, histerids). The recognition that reoccurring taxa exist and that they are found in forensically important groups is an early step toward factoring in their potential importance in future entomological investigations. Second, temporal changes in the taxonomic composition of the carrion-arthropod community were studied by quantifying the degree of taxonomic similarity between pairwise combinations of time-specific samples of the succession. In 13 of the 18 illustrated cases, the midsuccessional samples, owing to their higher species richness, were taxonomically more similar to all other pairwise samples, on the average, than early and late successional samples which were poorer in species. Variability in taxonomic composition is the norm for most periods of the succession; however, in 17 of the 23 cases, some successional periods (particularly endpoint samples) revealed no changes in arthropod species composition (= matching sample-pairs). When applied to medicolegal cases, it is suggested that data sets with large fractions of matching sample-pairs should produce wider-ranging PMI estimates, on the average, than data sets with smaller fractions of matching sample-pairs. Third, Monte Carlo simulation was applied to each of the 23 assemblages to test specific hypotheses about community-wide patterns of arthropod visitation times on nonhuman carcasses. Simulation results revealed that arthropod residence times in the majority of cases (13 or 56%) followed a "clumped" succession model, whereas, the remaining 10 cases (44%) showed a more "uniform" spacing pattern of residence times on carcasses. Comparison of species accumulation curves for observed and simulated data further revealed that among the 13 "clumped" cases, most (9 or 69%) followed a "clumped, early" model (rather than "clumped, midterm" or "clumped, late" models).(ABSTRACT TRUNCATED AT 400 WORDS)     

家猪死后脑组织GC-MS检测和死亡时间推断的研究

目的利用GC-MS检测死后家猪脑组织的代谢产物,推断死亡时间。方法成年家猪大脑,置于25℃、75%RH的人工气候箱中,于0 h-84 h内,每间隔6 h取材,GC-MS检测各时间点脑组织代谢物变化。结果PCA显示:平台期和窗口期的时间组彼此分开。建立PLS模型,通过VIP> 1且Kruskal-Wallis检验(P <0.05)筛选出18种重要的代谢物,线性回归模型和参数检验均有统计学意义。多元回归方程为:Y_(PMI)=6.610+16.29X_(十八烷酸)+14.56X_(5-氨基缬草酸)+5.517X_(丙氨酸)(R~2=0.909、SE=6.323)或Y_(PMI)=15.78+9.690 X_(5-氨基缬草酸)+86.45X_(亮氨酸)-82.35X_(甘氨酸)(R~2=0.952、SE=4.271)。结论 GC-MS检测出家猪死后脑组织的多种产物与PMI存在显著相关性,证实了其理论和技术推断PMI的可行性。综合多指标多元逐步回归分析和PLS-DA等多元模式分析方法建立PMI推断模型,可提高推断模型的准确性和精确度。     

大鼠脑细胞DNA含量与死亡时间关系的图像分析

运用计算机图像分析技术 ,对大鼠死后脑细胞DNA的变化进行观测 ,以寻找一种客观、量化的推断早期死亡时间的标准。实验选择 1 5只大鼠。处死后 ,在 2 4h内每隔 1h分别取脑细胞进行细胞学涂片、福尔马林液固定、Feulgen染色、自动图象分析仪测量、统计学处理。结果显示 :大鼠的早期死亡时间与其脑细胞DNA降解速率呈线性关系 ,其中积分光密度 (IOD)、平均灰度 (AG)、异形指数 (ID)提示本法有可能作为精确推断死亡时间 (PMI)的辅助手段。     

Compound muscle action potential analysis in different death models: significance for the estimation of early postmortem interval

In this experimental study, we investigated the varieties of excitability of gastrocnemius muscle via sciatic nerve as per different death models (asphyxia, abundant-bleeding and gradual-bleeding) on rats and the significance for the estimation of postmortem interval was evaluated. For this purpose, the rats were applied different stimulus intensities (5, 20, 40 mA) with 0.1 ms duration, before, during and every 5 min after death, using rectangular impulses, and the mean amplitude, onset latency and area values for each compound muscle action potential (CMAP) were elicited. It was detected that amplitude and area increased and onset latencies prolonged in the first postmortem 15 min. From the 15 min, CMAP area and amplitude showed an ever-increasing decrease and the prolongation of onset latencies became apparent. The decrease rate of area and amplitude was found to be statistically significantly different in asphyxia and abundant-bleeding models compared with in gradual-bleeding model, at 30 min measurements. However, there was not any significant difference in onset latency increase rates of three groups. Separately, any significant correlation between the agony and excitability periods among the groups could not be detected. The fact that the increase rate of onset latency did not show a significant difference as per death models indicated that onset latency ratios would be more appropriate criteria in determination of postmortem interval, regardless the reason of death.     

大鼠脑细胞DNA含量与死亡时间关系的图像分析

应用计算机图像分析技术 ,测定 15只大鼠死后 48h内不同时间点大鼠脑细胞核DNA含量的面积(Area)、等效直径 (Mean Dia ,MD)、异形指数 (Indexofdensity ,ID)、平均光度 (Averageopticaldensity ,AOD)、积分光度 (Integralopticaldensity ,IOD)、密度变化数 (L Den Coe ,LDC)和平均灰度 (Averagegray ,AG)等七项参数的变化值。结果证明 ,在大鼠死亡后 2 8h内 ,其脑细胞核DNA降解速率与PMI具有一定相关性。将每个参数的测量值进行多项式运算 ,获得了更能体现DNA降解趋势的二项式回归方程。其结果表明 ,应用计算机图像分析技术 ,测量机体死后DNA含量变化 ,将会成为推断PMI精确、客观的新方法。     

A protocol for the forensic analysis of condom and personal lubricants found in sexual assault cases.

In sexual assault cases, lubricant trace evidence may supplement biological evidence, or may be the primary physical evidence where biological evidence is unavailable. This study considered a total of 50 lubricants from condoms and personal lubricant products available in Australia. Differentiation of the samples was attempted using fluorescence examination, Fourier transform infrared spectroscopy (DRIFTS), gas chromatography-mass spectrometry, liquid chromatography-tandem mass spectrometry, and pyrolysis gas chromatography-mass spectrometry. Eleven of the samples were uniquely identified by the analysis scheme, while the remainder of the samples were separated into nine groups. As a result of this study, a recommended protocol for the detection and analysis of an "unknown" biological swab was produced.     

大鼠肝细胞DNA含量与早期死亡时间关系的图像分析研究

实验选择 15只大鼠 ,处死后 ,在 2 4h内 ,每隔 1h取肝组织块进行细胞学涂片、福尔马林液固定、Feul gen染色、自动图像分析仪测量、统计学处理数据。结果表明 ,肝细胞DNA含量在死后 2 4h内 ,随死亡时间的延长而较有规律的下降。其中积分光密度、平均光密度、异形指数是用来研究死亡 2 4h内肝细胞DNA降解规律 ,并准确推断死亡时间的较好指标。     

人体死后肝细胞DNA含量与死亡时间关系的研究

目的研究人体死后肝脏细胞DNA含量变化与死亡时间的关系及影响因素。方法选取46例已知死亡时间的人体肝脏,根据离体肝脏所处的环境温度分为12—19％（A组）和20—27％（B组）两组,每组23例。在死后24～72h内每隔4h穿刺取肝组织1次,制成细胞悬液,经RNA酶消化,PI染色后,用流式细胞仪测定被检测细胞中含不完整DNA的细胞数所占百分比,所得数据经Exp032V1．2软件计算N值。结果死后24～72h肝细胞N平均值,A组从10．91％增至49．72％,B组从16．22％增至69．63％。两组N平均值随死亡时间的延长均逐渐增高,与死亡时间有相关性,A组r值为：0．598,B组r值为0．77357。并且建立了不同环境温度对应的回归方程。结论在不同环境温度下,死后24～72h内人体肝脏细胞DNA降解均随死亡时间的延长和环境温度的升高而逐渐加快,相关数据可望为死亡时间推断提供一定参考依据。     

Cooling rates of the ear and brain in pig heads submerged in water: implications for postmortem interval estimation of cadavers found in still water

The state of the art for determining postmortem interval in submerged bodies reflects a serious lack of studies. The objectives of the present study were therefore to study cerebral and tympanic cooling in water and its relation to cooling in air, in a pig model. First of all, cerebral and tympanic cooling on a single head and on an entire body were compared and proven to be very similar in air and in water. Nine pairs of heads were then exposed to 9 temperature intervals from 0 degrees C to 20 degrees C. For every set temperature, one head was placed in water, the other in "ambient" air in a thermostatic chamber. Ear and brain temperature were simultaneously measured every 10 minutes during 8 hours. Results showed that both in air and in water, cooling curves were almost exponential, regardless of the site (ear or brain) or the environmental temperature. Cooling was always more rapid in water than in air. Cerebral and tympanic cooling always had a correlation coefficient of 0.98-0.99. Assuming that these cooling patterns are applicable to man, this research may provide a starting point for postmortem interval estimation in submerged cadavers.     

Population data on the forensic genetic markers: phosphoglucomutase-1, esterase D, erythrocyte acid phosphatase and glyoxylase I

Blood specimens from white and black sample populations from Baltimore, Maryland, were analyzed for the four most forensically important, polymorphic red cell enzyme systems-phosphoglucomutase-1, esterase D, erythrocyte acid phosphatase and glyoxalase I. The distributions of the phenotypes for each marker in each racial group were in Hardy-Weinberg equilibrium. The population data were similar to previously reported data for Whites and Blacks from different geographical locations within the United States.     

Inference structures for crime analysis and intelligence: the example of burglary using forensic science data

There has been much work dedicated to crime analysis and intelligence in recent times. Independently, physical evidence has shown great potential for linking crimes and bringing solid informative data through the increased use of multiple databases. However, their informative potential is still often underestimated and has been poorly integrated into police information systems. We propose a framework that fully introduces this data into an intelligence based system. This framework is built on the study of inference structures extracted from investigators’ every day implicit reasoning processes. Five specific inferences are studied with the particular problem of serial burglary investigation across independent police and legal structures. On the basis of such an analytical approach, a computer prototype has been designed; it has shown great promise and has resulted in several operational successes.     

In vitro loss of potassium from erythrocytes during the 0-108 h postmortem period in rats: relationship between potassium loss and postmortem interval.

A simple technique was employed for measurement of potassium loss (K(los)s) from normal and from postmortem rat erythrocytes during controlled exposure to physiologically isosmotic NaCl solution. Potassium loss from the cells decreased in a (non-linear) time-related manner during the 0-108 h postmortem period; expression of the data in the form of a double logarithmic plot (log K(loss) versus log postmortem interval (PMI) linearized the relationship between 18 and 108 h post mortem (r = -0.86; P less than 0.001 (n = 24)). Experimental data revealed that the observed postmortem changes in K(loss) were associated with and probably resulted from, the postmortem decrease in magnitude of the potassium concentration gradient across the erythrocyte membrane. Attention is drawn to the possibility of utilizing measurements of in vitro loss of potassium from erythrocytes as a means of estimating time elapsed since death.     

Forensic data management and database systems in forensic investigations for cases of missing and unidentified persons in Brazil

Forensic investigations, especially those related to missing persons and unidentified remains, produce different types of data that must be managed and understood. The data collected and produced are extensive and originate from various sources: the police, non-governmental organizations (NGOs), medical examiner offices, specialised forensic teams, family members, and others. Some examples of information include, but are not limited to, the investigative background information, excavation data of burial sites, antemortem data on missing persons, and postmortem data on the remains of unidentified individuals. These complex data must be stored in a secured place, analysed, compared, shared, and then reported to the investigative actors and the public, especially the families of missing persons, who should be kept informed of the investigation. Therefore, a data management system with the capability of performing the tasks relevant to the goals of the investigation and the identification of an individual, while respecting the deceased and their families, is critical for standardising investigations. Data management is crucial to assure the quality of investigative processes, and it must be recognised as a holistic integrated system. The aim of this article is to discuss some of the most important components of an effective forensic data management system. The discussion is enriched by examples, challenges, and lessons learned from the erratic development and launching of databases for missing and unidentified persons in Brazil. The main objective of this article is to bring attention to the urgent need for an effective and integrated system in Brazil.     

Effects of refrigeration on the biometry and development of Protophormia terraenovae (Robineau-Desvoidy) (Diptera: Calliphoridae) and its consequences in estimating post-mortem interval in forensic investigations

The aim of this study was to simulate the low temperatures that insects could experience between the time being sampled from cadavers and their arrival in the laboratory. This was in order to investigate the effect of low temperature on development of maggots. At different stages of development, individuals of Protophormia terraenovae (Robineau-Desvoidy) reared at 24 degrees C were submitted to a temperature of 4.0+/-0.5 degrees C for a period varying from 1 to 10 days. Independent of the stage of development at which the insects were refrigerated, the treatment induced significant changes on the duration of development. The effect of low temperature on the developmental time between the return to 24 degrees C to adult emergence depended on the larval stage that was refrigerated. When first instar larvae and prepupae were refrigerated, the time to emergence at 24 degrees C decreased with an increase of duration of the refrigeration period. Time to emergence increased under the same conditions when second instar larvae and pupae were refrigerated. These results indicate that keeping larvae of P. terraenovae at 4 degrees C does not just simply lead to a cessation of metabolism but disturbs the regular development. Ten days of cooling induced an error in estimating post-mortem interval (PMI) of more than 6h.     

人脾脏细胞核DNA含量与死亡时间关系的图像分析

目的研究人脾脏细胞DNA含量改变与死亡时间的关系。方法选取36例已知死亡时间的人体脾脏,在死后5～36h内逐时进行细胞学涂片、Feulgen Vans染色观察,并用图像分析系统,测定脾脏细胞核积分光密度、平均灰度等灰度参数,所得数据用SPSS软件分析。结果在5～36h内平均光密度、积分光密度、平均灰度均值均与死亡时间显著性相关,并得出对应的回归方程,其中平均光密度、积分光密度随死亡时间的延长而逐渐减小、平均灰度逐渐增大。结论人脾脏细胞核DNA含量改变呈现一定规律,与死亡时间明显相关。     

A selection of some of Dr. McCrone's high and low profile cases in the forensic analysis of art

Throughout Dr. McCrone's active professional career of over 60 years, he worked on many cases involving the forensic analysis of art. This is an overview of a small portion of these cases. Included (exposed as fakes) are the Shroud of Turin, the Vinland Map, Mayan pottery illustrations and Larionov pastels. Also included, with strong support for authentication, are three paintings attributed to Manet, Giorgione, and Leonardo da Vinci.