Methyl tert‐Butyl Ether (MTBE) Detected in Abnormally High Concentrations in Postmortem Blood and Urine from Two Persons Found Dead Inside a Car Containing a Gasoline Spill

Two deep frozen persons, a female and a male, were found dead in a car. There had been an explosive fire inside the car which had extinguished itself. On the floor inside the car were large pools of liquid which smelled of gasoline. The autopsy findings and routine toxicological analyses could not explain the cause of death. Carboxyhemoglobin levels in the blood samples were <10%. Analysis with a headspace gas chromatography revealed methyl tert‐butyl ether (MTBE) concentrations of 185 mg/L (female victim) and 115 mg/L (male victim) in peripheral blood. The urine MTBE concentrations were 150 mg/L and 256 mg/L, respectively. MTBE is a synthetic chemical which is added to gasoline as a fuel oxygenate. Gasoline poisoning is likely to be the cause of the death in these two cases, and MTBE can be a suitable marker of gasoline exposure, when other volatile components have vaporized.     

Assessing the Risk of Secondary Transfer Via Fingerprint Brush Contamination Using Enhanced Sensitivity DNA Analysis Methods

Experiments were performed to determine the extent of cross‐contamination of DNA resulting from secondary transfer due to fingerprint brushes used on multiple items of evidence. Analysis of both standard and low copy number (LCN) STR was performed. Two different procedures were used to enhance sensitivity, post‐PCR cleanup and increased cycle number. Under standard STR typing procedures, some additional alleles were produced that were not present in the controls or blanks; however, there was insufficient data to include the contaminant donor as a contributor. Inclusion of the contaminant donor did occur for one sample using post‐PCR cleanup. Detection of the contaminant donor occurred for every replicate of the 31 cycle amplifications; however, using LCN interpretation recommendations for consensus profiles, only one sample would include the contaminant donor. Our results indicate that detection of secondary transfer of DNA can occur through fingerprint brush contamination and is enhanced using LCN‐DNA methods.     

Forensic Comparison of Soil Samples Using Nondestructive Elemental Analysis

Soil can play an important role in forensic cases in linking suspects or objects to a crime scene by comparing samples from the crime scene with samples derived from items. This study uses an adapted ED‐XRF analysis (sieving instead of grinding to prevent destruction of microfossils) to produce elemental composition data of 20 elements. Different data processing techniques and statistical distances were evaluated using data from 50 samples and the log‐LR cost (C_llr). The best performing combination, Canberra distance, relative data, and square root values, is used to construct a discriminative model. Examples of the spatial resolution of the method in crime scenes are shown for three locations, and sampling strategy is discussed. Twelve test cases were analyzed, and results showed that the method is applicable. The study shows how the combination of an analysis technique, a database, and a discriminative model can be used to compare multiple soil samples quickly.     

Drug Contamination of U.S. Paper Currency and Forensic Relevance of Canine Alert to Paper Currency: A Critical Review of the Scientific Literature

Several studies have reported on wide‐spread contamination of U.S. paper currency with cocaine and to a lesser extent other illicit drugs. Canines are trained and employed to search for and alert to drugs. Canine alert to currency has been used as evidence that currency has been directly involved in illicit drug trafficking to justify currency seizure and forfeiture. This assertion, particularly when the only evidence is based upon canine alert, has been challenged in the courts considering that most currency in circulation is contaminated with cocaine. Comprehensive review of the scientific literature establishes that (i) 67–100% of circulated U.S. currency is contaminated with cocaine ranging from a few nanograms to over one milligram/bill (ii) various biological and environmental parameters impact canine alert to drugs. It is concluded that canine alert to U.S. currency is not sufficiently reliable to determine that currency was directly used in an illicit drug transaction.     

Characteristics of Forensic Imaging Performance—An Analysis of Forensic Imaging Bottlenecks

Disk imaging involves copying all of the data from a source disk drive to a target. Typically, the target for the copy is another disk drive. Forensic processes developed years ago do not appear to be adequate for current storage technology. For example, with disk drive capacities now exceeding 1 Terabyte, a typical disk imaging can take over 8 hours at typical rates. With disk drive capacities increasing, forensic copying is expected to take even longer. Along with increase in disk capacity, the industry has also seen an increase in data transfer rates. In many cases, forensic imaging is taking longer than necessary. To identify the bottlenecks, an examination of different methods used to transfer data from a source disk was performed. Factors considered were differing disk access technologies. One finding is that the USB disk access technology (version 2.0 and earlier) is a significant bottleneck for data transfer rates, especially when the USB device is a write‐blocker. Other factors that contribute to the efficiency of a forensic copy are the file system used to write a forensic image and the data transfer size used when reading from a disk drive. Optimal parameters for performing a forensic acquisition from a disk drive are identified.     

Forensic Biomechanical Analysis of Falls from Height Using Numerical Human Body Models*

Abstract: This article describes the method of using human body models developed originally for the use in automotive safety in forensic reconstructions of falls from height. The MADYMO^® software package and multibody human body models were used in forensic analyses of two real cases—a fatal fall from a window c. 13.8 m above the ground and a fall into a c. 2.5‐m deep cellar pit resulting in isolated ankle joint injury. The performed series of numerical simulations helped to reconstruct the events and to resolve legally relevant questions concerning various aspects of the falls. The benefits as well as limitations and potential biases associated with the use of numerical simulation in forensic biomechanical settings are discussed. The method has proven to be effective under specific circumstances, though the cost (both financial and temporal) still prevents it from wider use.     

The Application of Flow Cytometry as a Rapid and Sensitive Screening Method to Detect Contamination of Vitreous Humor Samples and Avoid Miscalculation of the Postmortem Interval

Research into maximizing the speed, precision, and reliability of estimating the postmortem interval (PMI) has been a recurring object of investigation and methodologies based on the vitreous humor (VH) have provided good results. However, contamination from causes not readily apparent, such as blood, can occur, and thus lead not only to an erroneous estimation of PMI, but also interfere with the correct identification of other substances in the VH. We have developed a flow cytometry method which quantifies blood contamination and is able to detect erythrocytes in 1:750,000 dilution of contaminated VH which affects the results of hypoxanthine. It is an improvement on the previous more complex mass spectrometry method, being faster, more sensitive, and readily available. As such, it could be proposed for the rapid screening of appropriate samples by detecting and eliminating blood contaminated samples from PMI estimation.     

Forensic Identification of Blood in the Presence of Contaminations Using Raman Microspectroscopy Coupled with Advanced Statistics: Effect of Sand,Dust, and Soil

Body fluid traces recovered at crime scenes are among the most common and important types of forensic evidence. However, the ability to characterize a biological stain at a crime scene nondestructively has not yet been demonstrated. Here, we expand the Raman spectroscopic approach for the identification of dry traces of pure body fluids to address the problem of heterogeneous contamination, which can impair the performance of conventional methods. The concept of multidimensional Raman signatures was utilized for the identification of blood in dry traces contaminated with sand, dust, and soil. Multiple Raman spectra were acquired from the samples via automatic scanning, and the contribution of blood was evaluated through the fitting quality using spectroscopic signature components. The spatial mapping technique allowed for detection of “hot spots” dominated by blood contribution. The proposed method has great potential for blood identification in highly contaminated samples.     

A Forensic Entomological Analysis Can Yield an Estimate of Postmortem Interval,and Not Just a Minimum Postmortem Interval: An Explanation and Illustration Using a Case

Several authors claimed that a forensic entomological analysis can never be interpreted as the postmortem interval (PMI), but that it can be interpreted as a minimum postmortem interval (PMI_min), or dead for not less than X amount of time. Because in most instances, a PMI estimate should be a range, that is, the set of values from maximum postmortem interval (PMI_max) to PMI_min, objections to PMI estimation are objections to PMI_max estimation. The arguments for this position did not address the substantial body of literature describing estimation of both PMI_max and PMI_min using insect succession analysis. This report reviews the scientific issues and presents a recent homicide investigation in which several forensic entomology experts used the absence of carrion insects on the corpse, a kind of succession analysis, to estimate PMI or PMI_max.     

Validation of the New Interpretation of Gerasimov's Nasal Projection Method for Forensic Facial Approximation Using CT Data,

The most common method to predict nasal projection for forensic facial approximation is Gerasimov's two‐tangent method. Ullrich H, Stephan CN (J Forensic Sci, 2011; 56: 470) argued that the method has not being properly implemented and a revised interpretation was proposed. The aim of this study was to compare the accuracy of both versions using a sample of 66 postmortem cranial CT data. The true nasal tip was defined using pronasale and nasal spine line, as it was not originally specified by Gerasimov. The original guidelines were found to be highly inaccurate with the position of the nasal tip being overestimated by c. 2 cm. Despite the revised interpretation consistently resulting in smaller distance from true nasal tip, the method was not statistically accurate (p > 0.05) in positioning the tip of the nose (absolute distance >5 mm). These results support that Gerasimov's method was not properly performed, and Ullrich H, Stephan CN (J Forensic Sci, 2011; 56: 470) interpretation should be used instead.     

Forensic Identification of Seal Oils Using Lipid Profiles and Statistical Models

Seal blubber oils are used as a source of omega‐3 polyunsaturated fatty acids in Canada but prohibited in the United States and (FA) European Union. Thus, a reliable method is needed to identify oils originating from seals versus fish. Two lipid profiling methods, fatty acid analysis using gas chromatography and triacylglycerol (TAG) analysis using liquid chromatography and mass spectrometry, were applied with statistical models to discriminate commercial oils and blubber samples harvested from marine fish and seals. Significant differences were observed among FA profiles, and seal samples differed from each of the fish oils (p ≤ 0.001). FA and TAG profiles were used to discriminate sample groups using a random forest classifier; all samples were classified correctly as seals versus fish using both methods. We propose a two‐step method for the accurate identification of seal oils, with preliminary identification based on FA profile analysis and confirmation with TAG profiles.     

Forensic Analysis of Stains on Fabric Using Direct Analysis in Real‐time Ionization with High‐Resolution Accurate Mass‐Mass Spectrometry

A rapid technique using direct analysis in real ‐ time (DART) ambient ionization coupled to a high ‐ resolution accurate mass‐mass spectrometer (HRAM‐MS) was employed to analyze stains on an individual's pants suspected to have been involved in a violent crime. The victim was consuming chocolate ice cream at the time of the attack, and investigators recovered the suspect's pants exhibiting splatter stains. Liquid chromatography with mass spectral detection (LC‐MS) and stereoscopic light microscopy (SLM) were also utilized in this analysis. It was determined that the stains on the pants contained theobromine and caffeine, known components of chocolate. A shard from the ceramic bowl that contained the victim's ice cream and a control chocolate ice cream sample were also found to contain caffeine and theobromine. The use of DART‐HRAM‐MS was useful in this case due to its rapid analysis capability and because of the limited amount of sample present as a stain.     

Ultrafast Amplification of DNA on Plastic Microdevices for Forensic Short Tandem Repeat Analysis

The majority of microfluidic devices used as a platform for low‐cost, rapid DNA analysis are glass devices; however, microchip fabrication in glass is costly and laborious, enhancing the interest in polymeric substrates, such as poly (methyl methacrylate) (PMMA), as an inexpensive alternative. Here, we report amplification in PMMA polymerase chain reaction (PCR) microchips providing full short tandem repeat profiles (16 of 16 loci) in 30–40 min, with peak height ratios and stutter percentages that meet literature threshold requirements. In addition, partial profiles (15 of 16 loci) were generated using an ultrafast PCR method in 17.1 min, representing a ~10‐fold reduction in reaction time as compared to current amplification methods. Finally, a multichamber device was demonstrated to simultaneously amplify one positive, one negative, and five individual samples in 39 min. Although there were instances of loci dropout, this device represents a first step toward a microfluidic system capable of amplifying more than one sample simultaneously.     

Forensic Performance Analysis of Load‐Limiting Devices in Automotive Seat Belt Retractors

The introduction of frontal airbags and seatbelt pretensioners for front seat occupants provided an opportunity to address injuries caused by seatbelt loading by introducing load‐limiters, which were intended to reduce belt loading while maintaining proper restraint. Investigation and forensic analysis of real‐world crashes identified that the implementation of these devices, in some circumstances, increased the potential of injury. This paper focuses on the trade‐offs of load‐limiters, that is, the reduction loading to the occupant versus the corresponding increase in seatbelt webbing and occupant movement. If the additional webbing introduced is not controlled, the risk of injury to the occupant is increased and could result in more frequent and severe injuries rather than a reduction. This paper quantifies the webbing introduced by load‐limiter activation through forensic analysis of the seatbelt involved in real‐world crashes and testing and assesses its effect on the injuries sustained by the occupant.     

The Power of Contextual Effects in Forensic Anthropology: A Study of Biasability in the Visual Interpretations of Trauma Analysis on Skeletal Remains

The potential for contextual information to bias assessments in the forensic sciences has been demonstrated, in several forensic disiplines. In this paper, biasability potential within forensic anthropology was examined by analyzing the effects of external manipulations on judgments and decision‐making in visual trauma assessment. Three separate websites were created containing fourteen identical images. Participants were randomly assigned to one website. Each website provided different contextual information, to assess variation of interpretation of the same images between contexts. The results indicated a higher scoring of trauma identification responses for the Mass grave context. Furthermore, a significant biasing effect was detected in the interpretation of four images. Less experienced participants were more likely to indicate presence of trauma. This research demonstrates bias impact in forensic anthropological trauma assessments and highlights the importance of recognizing and limiting cognitive vulnerabilities that forensic anthropologists might bring to the analysis.     

The Potential of X‐Ray Diffraction in the Analysis of Burned Remains from Forensic Contexts*

Abstract: In view of the difficulties in extracting quantitative information from burned bone, we suggest a new and accurate method of determining the temperature and duration of burning of human remains in forensic contexts. Application of the powder X‐ray diffraction approach to a sample of human bone and teeth allowed their microstructural behavior, as a function of temperature (200–1000°C) and duration of burning (0, 18, 36, and 60 min), to be predicted. The experimental results from the 57 human bone sections and 12 molar teeth determined that the growth of hydroxylapatite crystallites is a direct and predictable function of the applied temperature, which follows a nonlinear logistic relationship. This will allow the forensic investigator to acquire useful information about the equilibrium temperature brought about by the burning process and to suggest a reasonable duration of fire exposure.     

Forensic Identification of CITES Protected Slimming Cactus (Hoodia) Using DNA Barcoding

Slimming cactus (Hoodia), found only in southwestern Africa, is a well‐known herbal product for losing weight. Consequently, Hoodia extracts are sought‐after worldwide despite a CITES Appendix II status. The failure to eradicate illegal trade is due to problems with detecting and identifying Hoodia using morphological and chemical characters. Our aim was to evaluate the potential of molecular identification of Hoodia based on DNA barcoding. Screening of nrITS1 and psbA‐trnH DNA sequences from 26 accessions of Ceropegieae resulted in successful identification, while conventional chemical profiling using DLI‐MS led to inaccurate detection and identification of Hoodia. The presence of Hoodia in herbal products was also successfully established using DNA sequences. A validation procedure of our DNA barcoding protocol demonstrated its robustness to changes in PCR conditions. We conclude that DNA barcoding is an effective tool for Hoodia detection and identification which can contribute to preventing illegal trade.     

Elemental Analysis of Variably Contaminated Cremains Using X‐ray Fluorescence Spectrometry

Analyzing and identifying skeletal remains becomes increasingly difficult when remains have been cremated, especially in cases where the cremated material may have been intentionally contaminated with nonskeletal material. This study examined the potential of X‐ray fluorescence spectrometry (XRF) to detect the presence of nonskeletal contaminants in samples of cremains. Eleven samples of cremains were variably combined with concrete mix and analyzed using XRF. Photon counts of elements in each sample were analyzed, and the coefficient of determination (R²) using unweighted linear regression as a function of percent cremains was calculated. Results showed that with changes in the proportion of skeletal material and contaminant, there were significant (R² > 0.90) changes in detected levels of phosphorus, potassium, zinc, aluminum, and sulfur. The use of XRF is concluded to be a valid approach in the identification of the presence of nonskeletal material in potentially contaminated cremains.     

Forensic Analysis of Cigarette Ash—Brand Determination Through Trace‐metal Analysis

The information inherent in cigarette ash in the form of trace‐metal concentrations may be of use in a forensic context as it can indicate the brand from which the ash originated. This knowledge might help place suspects at crime scenes or determine how many people may have been present. To develop and test statistical models capable of classifying ash samples according to brand, commercial cigarettes procured in the U.S. and overseas were “smoked” using a peristaltic pump, mimicking the range of human smoking habits. Ash samples were digested in a mixture of nitric and hydrochloric acid applying microwave digestion and analyzed using inductively coupled plasma‐mass spectrometry. Principal component analysis of the elemental data showed intrinsic differences between brands. Partial least squares‐discriminant analysis demonstrated that brand classification yields good sensitivity and specificity for a number of models tested. Varying smoking parameters did not impact the classification of ash samples.     

Comparative Forensic Soil Analysis of New Jersey State Parks Using a Combination of Simple Techniques with Multivariate Statistics,

This study has shown that the combination of simple techniques with the use of multivariate statistics offers the potential for the comparative analysis of soil samples. Five samples were obtained from each of twelve state parks across New Jersey in both the summer and fall seasons. Each sample was examined using particle‐size distribution, pH analysis in both water and 1 M CaCl₂, and a loss on ignition technique. Data from each of the techniques were combined, and principal component analysis (PCA) and canonical discriminant analysis (CDA) were used for multivariate data transformation. Samples from different locations could be visually differentiated from one another using these multivariate plots. Hold‐one‐out cross‐validation analysis showed error rates as low as 3.33%. Ten blind study samples were analyzed resulting in no misclassifications using Mahalanobis distance calculations and visual examinations of multivariate plots. Seasonal variation was minimal between corresponding samples, suggesting potential success in forensic applications.