Use In Forensic Investigations Research Articles

Determination of sex difference from fingerprint ridge density in northeastern Thai teenagers

Abstract: Although, there has already been much research on the differences between sexes in fingerprint ridge density and its variability in the Thai population, such studies have not included native northeastern Thais aged between 14 and 24 who are descended from northeastern Thai ancestry. This study intends to determine the topological, age-grouping and sexual differences in fingerprint ridge density (RD) in such populations. Fingerprints were collected from 353 unrelated volunteers (191 males and 162 females) and classified into three groups, that is, group A (total subjects), group B (14–18 years old) and group C (18–24 years old). RD was assessed for two topological areas, radial and ulnar. Significant differences between genders and age groups were obtained in both counting areas. Females exhibit higher RD i.e. narrower ridges, than males. A decrease in RD values with increasing age was also detected. The RD threshold for discrimination of sexes, computed based on Bayes’ theorem, was achieved in all groups and counting areas, enabling its use in forensic investigation.

The Potential of High-throughput Metagenomic Sequencing of Aquatic Bacterial Communities to Estimate the Postmortem Submersion Interval.

Human remains can be discovered in freshwater or marine ecosystems, circumstances where insects and other invertebrates have infrequently been used for understanding the time of postmortem submersion. In this study, the identification and succession of epinecrotic bacterial communities on vertebrate remains were described during decomposition in a temperate headwater stream during two seasons (summer and winter). Bacterial communities were characterized with 454 pyrosequencing and analyzed at phyletic and generic taxonomic resolutions. There was a significant increase in genera richness over decomposition during both seasons. Additionally, multivariate statistical modeling revealed significant differences in bacterial communities between seasons at both taxonomic resolutions and siginificant genera differences among sampling days within each season, suggesting a succession of these communities. These data are the first to describe aquatic bacterial succession using high-throughput metagenomic sequencing on vertebrate remains submerged in a freshwater habitat, and provide initial evidence for their potential use in forensic investigations.

HemoVision: An automated and virtual approach to bloodstain pattern analysis

Bloodstain pattern analysis (BPA) is a subspecialty of forensic sciences, dealing with the analysis and interpretation of bloodstain patterns in crime scenes. The aim of BPA is uncovering new information about the actions that took place in a crime scene, potentially leading to a confirmation or refutation of a suspect's statement. A typical goal of BPA is to estimate the flight paths for a set of stains, followed by a directional analysis in order to estimate the area of origin for the stains. The traditional approach, referred to as stringing, consists of attaching a piece of string to each stain, and letting the string represent an approximation of the stain's flight path. Even though stringing has been used extensively, many (practical) downsides exist. We propose an automated and virtual approach, employing fiducial markers and digital images. By automatically reconstructing a single coordinate frame from several images, limited user input is required. Synthetic crime scenes were created and analysed in order to evaluate the approach. Results demonstrate the correct operation and practical advantages, suggesting that the proposed approach may become a valuable asset for practically analysing bloodstain spatter patterns. Accompanying software called HemoVision is currently provided as a demonstrator and will be further developed for practical use in forensic investigations.

Locating Buried Canine Remains Using Ground Penetrating Radar

Ground penetrating radar (GPR) is a valuable geophysical tool to assist in the search for buried targets, including clandestine graves. Its use in forensic investigations has been limited due to a misconception of its capabilities and a lack of understanding of the limitations associated with its use. This case report details the application of GPR for locating buried canine remains at the request of the Ontario Provincial Police (OPP) in Canada. The canine was a police dog killed in the line of duty in 1975. His remains had been buried in a casket with concrete poured over the top prior to burial, however the exact location of the burial site was unknown. A Sensors and Software Smart Cart 500 MHz GPR system was used to locate the grave site on the front lawn of the OPP North Bay Detachment. The GPR data was collected in an X-Y grid format and analysed using Sensors and Software Ekko Mapper 4. This program allows the plots to be viewed from a bird's eye view as depth slices rather than cross sections of the soil. Identification of the grave site allowed for the canine's remains to be exhumed, cremated, and subsequently relocated to the OPP Museum in Orillia.

Reliable and Robust Molecular Sexing of the Hen Harrier (Circus cyaneus) Using PCR‐RFLP Analysis of the CHD 1 Gene

The hen harrier (Circus cyaneus) is a bird of prey that is persecuted in the United Kingdom, and there is a need for a DNA-based individual identification and sexing system for the use in forensic investigations. This study reports a new set of PCR primers for the chromo-helicase-DNA-binding protein 1 gene, which allows sexing using PCR-RFLP. Instead of exonic primers that amplify across a large intron, this set consists of a primer within the intron, enabling reduction in amplicon sizes from 356 to 212bp and 565 to 219bp in W and Z chromosomes. DNA degradation and dilution experiments demonstrate that this set is significantly more robust than one that amplifies across the intron, and sequencing of the intronic primer-binding region across several individuals shows that it is highly conserved. While our objective is to incorporate this primer set into an STR-based individualization kit, it may in the meantime prove useful in forensic or conservation studies.

Tooth Cementum Annulation for Estimation of Age‐at‐Death in Thermally Altered Remains

Assessment of tooth cementum annulations (TCA) is acknowledged for its potential as a more accurate method for estimating age-at-death than conventional macroscopic methods typically employed. Thermal alteration of remains in a forensic context is not uncommon; however, the use of TCA in heat-treated remains has hitherto received no quantitative assessment of accuracy. This study applies TCA to a sample of modern teeth of known demographics after experimental heat treatment at 600, 800 and 1000°C. Cementum annulations do survive thermal alteration; however, their visibility is dependent on exposure temperature. Physical and chemical changes resulted in TCA being applicable to only 63.3% of samples. An overall correlation to known age of r = 0.522 (p < 0.05) was found, while correlations of r = 0.868 (p < 0.01), r = 0.249, and r = -0.185, were found for 600, 800, and 1000°C subsets, respectively. These results indicate that in teeth exposed to temperatures >600°C, TCA no longer yields accurate enough results to be of use in forensic investigations.

Estimating sex of the human skeleton based on metrics of the sternum

Estimating the sex of skeletal remains is critical in creating the biological profile of an adult individual. Previous research has shown that analyzing the sternum may lead to an accurate estimation of sex based on studies performed on various populations around the globe, such as Indian, European, African, Canadian and North American. The motivation of the current study is to develop classification functions and sectioning points for use in forensic investigations in the United States. The majority of previously published methods are population specific, meaning the data would not prove useful in the United States. For this study, sternal measurements were collected from the William M. Bass Donated Skeletal Collection located at The University of Tennessee, Knoxville following the metric definitions provided by Schwartz and Bass. This collection consists of recent skeletal remains with known age at death, ancestry and sex. Material for the present study consisted of 410 human sterna: 285 male (256 American White/29 American Black) and 125 female (120 American White/5 American Black). Previous studies analyze the applicability of Hyrtl's law in the estimation of sex. This law follows that the mesosternum is greater than twice the length of the manubrium in males and in females the length of the manubrium is greater than half the length of the mesosternum. In this study, comparisons of the proportion of the length of the manubrium to the length of the mesosternum were performed to determine if Hrytl's law is applicable in an American population. Comparisons of these measurements between individuals identified as American Black and American White were analyzed to determine whether this method could be used on both population groups. Further, discriminant function analysis was used to estimate sex and provide a population specific classification function for use in the United States. The discriminate function analysis produced an overall cross-validation classification rate of 84.12% for sex estimation. The cross-validation classification rate for males and females was 80.00% and 88.24%, respectively.

Tracking Cats: Problems with Placing Feline Carnivores on δ18O, δD Isoscapes

BackgroundSeveral felids are endangered and threatened by the illegal wildlife trade. Establishing geographic origin of tissues of endangered species is thus crucial for wildlife crime investigations and effective conservation strategies. As shown in other species, stable isotope analysis of hydrogen and oxygen in hair (δDh, δ18Oh) can be used as a tool for provenance determination. However, reliably predicting the spatial distribution of δDh and δ18Oh requires confirmation from animal tissues of known origin and a detailed understanding of the isotopic routing of dietary nutrients into felid hair.Methodology/FindingsWe used coupled δDh and δ18Oh measurements from the North American bobcat (Lynx rufus) and puma (Puma concolor) with precipitation-based assignment isoscapes to test the feasibility of isotopic geo-location of felidae. Hairs of felid and rabbit museum specimens from 75 sites across the United States and Canada were analyzed. Bobcat and puma lacked a significant correlation between H/O isotopes in hair and local waters, and also exhibited an isotopic decoupling of δ18Oh and δDh. Conversely, strong δD and δ18O coupling was found for key prey, eastern cottontail rabbit (Sylvilagus floridanus; hair) and white-tailed deer (Odocoileus virginianus; collagen, bone phosphate).Conclusions/SignificancePuma and bobcat hairs do not adhere to expected pattern of H and O isotopic variation predicted by precipitation isoscapes for North America. Thus, using bulk hair, felids cannot be placed on δ18O and δD isoscapes for use in forensic investigations. The effective application of isotopes to trace the provenance of feline carnivores is likely compromised by major controls of their diet, physiology and metabolism on hair δ18O and δD related to body water budgets. Controlled feeding experiments, combined with single amino acid isotope analysis of diets and hair, are needed to reveal mechanisms and physiological traits explaining why felid hair does not follow isotopic patterns demonstrated in many other taxa.

Analysis of Forensic SNPs in the Canine mtDNA HV1 Mutational Hotspot Region*

A 60 bp sequence variation hotspot in the canine mitochondrial DNA hypervariable region 1 was evaluated for its use in forensic investigations. Nineteen haplotypes containing 18 single nucleotide polymorphisms were observed among laboratory-generated and GenBank-derived domestic dog sequences representing five regional localities in the U.S. Samples from the different localities were highly variable with the levels of intra-population variability being similar among the populations studied. AMOVA further confirmed that there was no significant genetic structuring of the populations. Assays using these haplotypes were robust, canid specific and portend a rapid method for correctly excluding individual dogs as noncontributors of forensic evidence. Species-specificity of the primers was confirmed by means of in-tube polymerase chain reaction of human and cat DNA and in-silico assessment of the genomes of several animal species. Breed-specific fragments were not detected among the common haplotypes but there is evidence that this assay may be capable of differentiating domestic dog, wolf, and coyote sequences.

Morphology of puparia of Megaselia scalaris (Diptera: Phoridae), a fly species of medical and forensic importance

Megaselia scalaris (Loew), a scuttle fly, is a fly species of medical and forensic importance. For use in forensic investigation, fly specimens found to associate with human corpses have to be identified at species level. Herein, we present the morphology of the puparia of the above fly species using scanning electron microscopy. The characteristic of the intersegmental spines along the dorsal and lateral segments and sculpture of the pupal respiratory horn of this puparia may be useful in future studies, to distinguish it from other closely related species.

Forensic geology of bone mineral: geochemical tracers for post-mortem movement of bone remains

Abstract The trace element chemistry of bone is rapidly altered post-mortem, and the post-mortem chemistry of bone mineral has been used successfully to discriminate between fossil bones removed from stratigraphically and spatially separate excavations. These techniques can be used to identify and protect scientifically or culturally sensitive artefacts. Measurable changes in the trace element composition of bone may occur within a few years of death. These changes show considerable potential for use in forensic investigations, particularly where post-mortem movement or scattering of bone remains has occurred. Early post-mortem alteration is complex, governed by a number of environmental variables, and measuring subtle changes in bone chemistry presents considerable analytical challenges. More work is needed in this area.

PROSTATE-SPECIFIC ANTIGEN: Its Discovery and Biochemical Characteristics

The search for a more sensitive and specific marker for prostate cancer as well as for use in forensic investigations led to the discovery of PSA. Utilization of the purified protein resulted in the development of many immunoassays that are now in widespread use and have been applied successfully to the detection and monitoring of prostate cancer. Subsequent investigation into the biochemical characteristics of PSA revealed free and complexed forms of PSA in serum whose measurement now may provide additional clinical benefit. Further research into the molecular and biochemical properties of PSA as well as improvements in measurement techniques no doubt will lead to new applications and enhanced clinical use for this important tumor marker.

HUMTH01 Validation Studies: Effect of Substrate, Environment, and Mixtures

New DNA typing methods need to be thoroughly validated prior to use in forensic investigation. This includes determining the effects different sample conditions have on the typeability of those samples. Biological samples routinely encountered in forensic case work were exposed to a series of different substrates, environmental conditions, and mixtures and typed for the STR HUMTH01 using PCR. None of the conditions resulted in a false typing or preferential allele amplification. It is demonstrated that the application of HUMTH01 typing methods in forensic case work can be reliable, robust, and efficient.

A Review of Identifying Plant Food Cells in Gastric Contents for Use in Forensic Investigations—A Laboratory Manual

Abstract This laboratory manual was developed to assist death investigators in determining what food, if any, was eaten prior to death by analysis of the gastric contents. It is intended for use by investigators not previously trained in histologic techniques. It is a step-by-step guide for the actual preparation of microscopic slides and identification of gastric materials.

The value of chorionic structure and size in the diagnosis of blowfly eggs

Chorionic structure and size can be of great value in the identification of the eggs of British blowflies of forensic importance. The most useful features are the shape and structure of the plastronic area between the hatching pleats. Correct identification of the eggs of the species considered here would be of use in forensic investigations, not only in Britain, but also in the wide area of the Holarctic region.

The use of remission analysis for direct colorimetric determination of age of blood stains (author's transl)

A review is given of the conventional methods of determining the age of blood stains by forensic examination of trace evidence. Detailed analysis of the samples in several steps, which destroyed the traces, and the widely differing results do not appear satisfactory with regard to their use in forensic investigations. Considering the change in color with increasing age the three coloric parameters (chroma, hue, and value of the blood stain) can yield exact numerical measurements which allow to draw relatively reliable conclusions as to the age of the blood stain. Of the three colorimetric methods, based on equalization, three regions, and spectral analysis, respectively, only the last may be considered really satisfactory and up to the requirements of forensic medicine. It has the additional advantage of being independent of the visual acuity of the examiner and of the type and quality of the source of illumination. The aging of freshly taken venous blood, which has been deposited on filter paper or linen, can last up to 33 days, either in the dark or in day light, with due regard to temperature and humidity. The spectrophotometric color measurements taken place on the immediate surface of the blood stain in the range of the visual spectrum between 400 and 600 nm. The continuously drawn spectral curves are then subject to remission analysis the first step. The second step consists in a mathematical computer analysis of color valence measurements.