Determining the order of deposition of natural latent fingerprints and laser printed ink using chemical mapping with secondary ion mass spectrometry

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) chemical mapping was used to investigate the order of deposition of natural latent fingerprints and laser printed ink on paper. This feasibility study shows that sodium, potassium and C₃H₅ positive ions were particularly abundant endogenous components of the natural fingerprints and also present in the paper examined, but were mostly absent in the laser printed ink. Mapping of these ions enables the observation of friction ridges from latent prints on the ink surface, only when a fingerprint was deposited above the layer of ink. As a demonstration of proof of concept, blind testing of 21 samples from three donors resulted in a 100% success rate. The sensitivity of this technique was investigated within this trial through the examination of up to fifth depletion fingerprints and ageing of up to 28 days. Migration of fingerprint and paper components to the ink surface, although observed with increased ageing time, was not found to compromise determination of the deposition sequence.     

A Small Population Study on Friction Skin Ridges: Differences in Ridge Widths Between Latent and Inked Fingerprints

Morphological changes in the width of latent fingermark ridges occur naturally over time. This could be used to examine the aging process of latents and eventually estimate time of deposition. In a crime context, it is common practice to compare a questioned (aged) fingermark with a database of known (inked) prints. Therefore, in the absence of fresh fingermarks for aging purposes, it is of interest to reveal correlations between these two categories of fingerprints with regard to the widths of their ridges. The present study explores correlations of ridge widths between flat and rolled inked prints with latent fingermarks visualized with carbon black (CB) and titanium dioxide (TiO₂)-based powders among a small population of ten donors. Results revealed consistent differences between the ridge widths of latent and inked prints as well as flat and rolled impressions. Latent fingermarks visualized with CB and TiO₂ powders showed ridges with comparable widths.     

Evaluation of the solvent black 3 fingermark enhancement reagent: Part 2 — Investigation of the optimum formulation and application parameters

A comparison is reported of the relative effectiveness to two formulations of the solvent black 3 (Sudan Black) reagent used to enhance grease contaminated fingermarks. These experiments compared the currently recommended ethanol-based formulation with a lower flammability system based on 1-methoxy-2-propanol (PGME) using natural, deliberately sebaceous and grease contaminated marks across a range of surfaces. It is shown that overall the PGME-based formulation was significantly better at producing good ridge detail on most surfaces for both natural and deliberately sebaceous prints, and for contaminated prints the ridge detail obtained with the PGME-based formulation was as good or better than that obtained with the ethanol formulation.Several smaller experiments were also carried out in order to provide additional information on the solvent black 3 process. These showed that solutions of age up to 2 years can still develop good ridge detail, but the colour of the stained mark may vary. It was also demonstrated that the currently recommended 2 minute treatment time often resulted in very heavy background staining and in practice significantly reduced treatment times can be recommended according to the nature of the surface present.     

Ridge Width Correlations between Inked Prints and Powdered Latent Fingerprints

A methodology to estimate the time of latent fingerprint deposition would be of great value to law enforcement and courts. It has been observed that ridge topography changes as latent prints age, including the widths of ridges that could be measured as a function of time. Crime suspects are commonly identified using fingerprint databases that contain reference inked tenprints (flat and rolled impressions). These can be of interest in aging studies as they provide baseline information relating to the original (nonaged) ridges’ widths. In practice, the age of latent fingerprints could be estimated following a comparison process between the evidentiary aged print and the corresponding reference inked print. The present article explores possible correlations between inked and fresh latent fingerprints deposited on different substrates and visualized with TiO₂. The results indicate that the ridge width of flat inked prints is most similar to fresh latent fingerprints_, and these should be used as the comparison standard for future aging studies.     

An investigation into the enhancement of fingermarks in blood on paper with genipin and lawsone

The abilities of two natural products, genipin and lawsone, to enhance blood contaminated fingermarks on papers of various porosities and colour were investigated and compared to the routinely used amino acid reagents, ninhydrin and 1,8-diazafluoren-9-one (DFO).Fingermarks in blood were deposited as a split depletion series on various paper types and colours for ageing periods of 6 weeks, 4 weeks, 2 weeks and 1 week before enhancement. The developed marks were observed under different lighting conditions, recorded and graded by way of attributing quantitative data to each series.Results indicated that while genipin showed some potential as a reagent for the enhancement of latent fingermarks, it displayed no suitability for the enhancement of fingermarks in blood on paper. Lawsone also failed to successfully enhance either type of fingermark. Upon comparison of the results with those of ninhydrin and DFO it was found that ninhydrin displayed the highest success rate of development of these marks.     

On the sensitivity of some common metallographic reagents to restoring obliterated marks on medium carbon (0.31% C) steel surfaces

Chemical etching, which is the most sensitive method to recover obliterated serial numbers on metal surfaces, has been practised quite successfully in forensic science laboratories all over the world. A large number of etchants suitable for particular metal surfaces based on empirical studies is available in the literature. This article reviews the sensitivity and efficacy of some popular etchants for recovering obliterated marks on medium carbon steel (0.31% C with ferrite–pearlite microstructure) used in automobile parts. The experiments involved engraving these carbon steel plates with some alphanumeric characters using a computer controlled machine “Gravograph” and erasing them to several depths below the bottom of their engraving depth. Seven metallographic reagents of which most of them were copper containing compounds were chosen for etching. The erased plates were etched with every one of these etchants using swabbing method. The results have revealed that Fry’s reagent comprising cupric chloride 90 g, hydrochloric acid 120 mL and water 100 mL provided the necessary contrast and was concluded to be the most sensitive. The same reagent was recommended by earlier workers for revealing strain lines in steel surfaces. Earlier, another reagent containing 5 g copper sulphate, 60 mL water, 30 mL (conc.) ammonium hydroxide, and 60 mL (conc.) hydrochloric acid was proved to be more sensitive to restore erased marks on low carbon steel (0.1% C with ferrite–pearlite structure) [M.A.M. Zaili, R. Kuppuswamy, H. Harun, Restoration of engraved marks on steel surfaces by etching technique, Forensic Sci. Int. 171 (2007) 27–32]. Thus the sensitivity of the etching reagent on steel surfaces appeared to be dependent on the content of carbon in the steel.     

Forensic DNA laboratory automation – Principles and guidelines

There is a lack of clear guidelines for project managers, laboratory managers and forensic scientists on strategies for the automation of forensic DNA laboratory processes and operational implementation of new technologies. This is reflected in the failure rate of projects in the forensic DNA testing environment. We present a set of guidelines and concepts important for forensic laboratory automation. Some case studies from past projects are presented. These consist of partial (or modular) automation (n = 2) and full automated robotically integrated systems (n = 2).Technology Management principles and concepts are crucial to prevent failure of projects, e.g. early adoption of untried technologies, and organizational factors. The future of laboratory automation is modular until such time as new discontinuous technologies will replace the need of the traditional manual laboratory configuration in totality.     

Pressing need for national governmental recognition of forensic anthropology in South Africa as illustrated in a medico-legal case

Forensic anthropology in South Africa is well developed in the higher education sector, with advanced training and research programmes. Despite this and decades of academic involvement in casework, forensic anthropology still lacks a defined framework and mandate at a governmental level. Therefore, the involvement of forensic anthropologists’ expertise varies markedly between cases, provinces, and among various stakeholders within the country, to the detriment of dispensation of social and criminal justice. The lack of clearly defined guidelines for the rendering of the service was exemplified and demonstrated through a recent forensic case. Here, contextual information was absent, and the remains posed a challenge to analyse, ostensibly due to missing information. Numerous questions were raised during the analysis of the remains, and broader concerns about the investigative involvement of a forensic anthropologist within South African casework were brought to the fore. Through the analysis of this case, we describe the deductive processes that led to the formation of an opinion that the skeletal linear defects were the result of taphonomic changes. In addition, we highlight how these efforts where constrained and each step in the process unnecessarily hindered. Finally, we demonstrate the capacity and willingness of forensic anthropology practitioners to be involved, and how, without governmental support, it is a great potential lamentably untapped.     

Longevity of spermatozoa in the post-ejaculatory urine of fertile men

Many scientists of varying clinical backgrounds have described the phenomenon of spermaturia in animals, adolescents as well as fertile and infertile men. Nevertheless, research for an expert opinion on a law case in the field of forensic medicine revealed a lack of valid information about the longevity of spermatozoa in post-ejaculatory urine (PEU) of fertile men.Our goal was to measure the appearance of vivid sperm in PEU while considering the factor of time in order to predict a realistic interval, in which positive sperm findings might occur. Therefore ten healthy, young men donated their sperm for fertility analysis and a urine sample prior to and after ejaculation. The time intervals between ejaculation and the first micturition were preset ranging between 30 min and maximal 11 h. Each ejaculate underwent a semen analysis. The pre- and post-ejaculatory urine samples were screened for the presence of viable and motile spermatozoa. Semen parameters were determined and related to the sperm findings in the precipitate of the urine samples. The amount, the viability and motility status of the detected spermatozoa were recorded after each preset time interval.The results showed that none of the 10 participants had sperm in their urine samples prior to ejaculation. The average sperm concentration was 50.1 ± 25.8 million/ml. After a time span of 30 min 59.5% of the first fractions of PEU samples were sperm positive, after 2 and 4 h still 70%, and after 5 h sperm were no longer detected. The last motile spermatozoa could be found after 4.5 h. It seems that remaining sperm in the urethra are washed out with the first micturition in the majority of fertile men, however, the conclusion as to whether sperm findings >5 h after ejaculation are improbable needs to be confirmed by further investigations.     

Soil forensics: How far can soil clay analysis distinguish between soil vestiges?

Soil traces are useful as forensic evidences because they frequently adhere to individuals and objects associated with crimes and can place or discard a suspect at/from a crime scene. Soil is a mixture of organic and inorganic components and among them soil clay contains signatures that make it reliable as forensic evidence. In this study, we hypothesized that soils can be forensically distinguished through the analysis of their clay fraction alone, and that samples of the same soil type can be consistently distinguished according to the distance they were collected from each other. To test these hypotheses 16 Oxisol samples were collected at distances of between 2 m and 1.000 m, and 16 Inceptisol samples were collected at distances of between 2 m and 300 m from each other. Clay fractions were extracted from soil samples and analyzed for hyperspectral color reflectance (HSI), X-ray diffraction crystallographic (XRD), and for contents of iron oxides, kaolinite and gibbsite. The dataset was submitted to multivariate analysis and results were from 65% to 100% effective to distinguish between samples from the two soil types. Both soil types could be consistently distinguished for forensic purposes according to the distance that samples were collected from each other: 1000 m for Oxisol and 10 m for Inceptisol. Clay color and XRD analysis were the most effective techniques to distinguish clay samples, and Inceptisol samples were more easily distinguished than Oxisol samples. Soil forensics seems a promising field for soil scientists as soil clay can be useful as forensic evidence by using routine analytical techniques from soil science.     

Experimental forensic studies of the preservation of pollen in vehicle fires

The implications of the recent recommendations of the Law Commission regarding the use of admissibility tests have the potential to be far reaching for forensic disciplines that rely on the expertise of highly qualified expert witnesses. These disciplines will need a concomitant body of peer-reviewed experiments that provides a basis for the interpretations of such evidence presented in court. This paper therefore, presents such results from two experiments which were undertaken to address specific issues that were raised in cases presented in the British courtroom. These studies demonstrate that there is a variability in the persistence of Lily, Daffodil and Tulip pollen when exposed to high temperatures between 0.5 min and 1440 min (24 h). It was possible to identify all three pollen types after 30 min of exposure to 400 °C, and after shorter time frames the threshold for successful identification was 700 °C after 0.5 min for all pollen types tested and 500 °C for Daffodil and Lily after 5 min of heat exposure. Over longer time periods (18 h (1080 min)) the different pollen types were found to persist in a viable form for identification at 300 °C (Lily), 200 °C (Daffodil) and 50 °C (Tulip). These findings, albeit from a small sample of pollen types, provide empirical contextual information that would contribute to such evidence having sufficient scientific weight to meet admissibility criteria and be viable evidence for a court. These studies demonstrate the value in seeking pollen evidence from even such extreme crime scenes as encountered in vehicular fires.     

Estimation of legal age using calcification stages of third molars in living individuals

The increased number of adolescents and young adults with unknown or inaccurately given date of birth is a current issue in justice and legal medicine. The objective of this study was to determine the extent to which third molar calcification stages assessed on panoramic X-rays could be useful as additional criteria for forensic age estimation in living individuals, focusing on the legally important ages 17 and 18.In a retrospective multi-center study, the developmental stage of each individual's third molar was analyzed using Demirjian's scale in 2360 cases. Additionally, sex, age and ancestry were assessed.Individuals with the lowest calcification stage of all present molars in stage H were ≥ 18 years with a likelihood of ≥ 99.05% in the female (n = 388), and ≥ 99.24% in the male (n = 482) population.The lowest calcification stage of all present third molars proved to be useful as an additional reliable criterion for the determination of an age ≥ 18 years.     

Genetic variation in a Japanese population,using the multiplex 24 STRs analysis system

Allele frequency distributions for 24 short tandem repeat (STR) loci were determined using the PowerPlex^R Fusion System (Promega) in 407 Japanese samples. The most informative locus among the 22 STR loci, excluding Amelogenin and DYS391, was Penta E (power of discrimination (PD) = 0.98), while the least informative was TPOX(PD = 0.831). The 22 loci combined matching probability (MP) was calculated to be 4.13 × 10⁻²⁶. These parameters indicated the usefulness of this 24 STR analysis in forensic personal identification and parentage testing among Japanese population.     

Soil sample metagenome NGS data management for forensic investigation

Soil analysis is a valuable resource in forensic investigation. Classical forensic soil analysis involves examination of its physical characteristics and chemical composition, such as soil type, colour, particle size, shape, pH, elemental, mineral and organic content. However the limited variability of these parameters is not always allowing adequate discrimination between soil samples. As soil supports extreme diversity of microorganisms and eukaryotic communities, microbiological approaches have been proposed. Several molecular approaches for microbial DNA profiling are available; however there is a lack of published data of implementation of the next generation sequencing (NGS) approaches for forensic soil analysis.The aim of the current study was elaboration of criteria for soil metagenome data management and database searching. We used our previously sequenced collection of 11 samples collected from different environments (forests, fields, grasslands, urban park) with different flora. The single sample collection includes 9 soil samples per one sampling area (30 m × 30 m) spaced by 15 m. In the current study we concentrated mainly on 18S rRNA gene V2-V3 region for fungi however SSU rRNA region for arbuscular mycorrhizal (AMF) fungi and V2-V3 hypervariable region of 16S rRNA gene for bacterial communities were taken into account. The sequencing was performed by Roche/454 platform. For data analysis OTU based approach on mothur software and NCBI BLASTN search were used. NCBI BLASTN analysis revealed altogether 2983 AMF matches and 8997 18S matches as well as 25477 OTUs (16S) were determined. Several data filtration approaches were used for data management. We found that 18S marker results could be used to create and run a filtered database that is computationally much more efficient and flexible. Our results have broad impact; however more samples have to be analysed, additional studies performed and cooperation between soil scientists and forensic scientists is required to be able to implement these novel techniques into the routine forensic practice.     

Repeatability and reproducibility of earprint acquisition

For all forensic disciplines dealing with identification -- e.g., of glass, tool marks, fibers, faces, fingers, handwriting, speakers -- in which manual (subjective, nonautomated) processes play a role, operator dependencies are relevant. With respect to earprint identification, in the period 2002-2005, the Forensic Ear Identification research project collected a database of 1229 donors, three prints per ear, and laid down a "best practice" for print acquisition. Repeatability and reproducibility aspects of the print acquisition are tested. The study suggests that different operators may acquire prints of differing quality, with equal error rates of the matching system ranging from 9% to 19%. Moreover, it turns out that "matching" earprints are more alike when taken in a consecutive row than when taken on separate occasions. This underlines the importance of (1) studying operator effects, (2) operator training, and (3) not gathering "matching" reference material at the same occasion.     

A brief study of time

In this paper we describe the first large-scale, long-term study of how hosts connected to the Internet manage their clocks. This is important for forensic investigations when there is a need for correlation of events collected from disparate sources, as well as for the correlation of computer events to “real” time. We have sampled over 8000 web servers on the Internet on a regular basis for a period of over six months. We have found that only about 74% of the hosts we observed were within 10 s of our reference time (UTC). The other hosts exhibited a large variety of different clock behaviors, some of which are explainable by existing clock models, some not, warranting further research in the area of forensic time and clock analysis.     

Characteristics of electrically injured skin from human hand tissue samples using Fourier transform infrared microspectroscopy

This technical note describes a method for distinguishing normal skin tissue samples from those electrically injured by Fourier transform infrared microspectroscopy (FTIR MSP). Furthermore, the infrared spectral features of electrically injured cells and tissues were evaluated to identify molecular changes in epidermal cells. In the present study, 20 human hand tissue samples were evaluated macroscopically and histopathologically. The electrically injured skin samples were subdivided into 2 regions [normal cell regions (NCRs) and polarized cell regions (PCRs)] and 14 major spectral absorption bands were selected. The spectral results showed that the band absorbance at 1080, 1126, 1172, 1242, 1307, 1403, 1456, 1541, 2852, 2925, 2957, 3075, and 3300 cm^− 1 increased significantly both in the stratum and non-stratum corneum of the PCRs in electrically injured skin tissues samples. No significant difference was found between normal skin and the NCR of the electrically injured skin samples. The band absorbance ratios of A₁₁₇₂/A₁₁₂₆, A₁₄₅₆/A₁₄₀₃, and A₂₉₂₅/A₂₉₅₇ were significantly increased, whereas the A₁₆₅₂/A₁₅₄₁ ratio was decreased in the PCR of the stratum corneum and non-stratum corneum. Baseline changes from 4000 to near 1737 cm^− 1 were observed in the spectra of the electrically injured skin samples, which were interpreted in terms of the pathological process involved in electrical injury. FTIR-MSP presents a useful method to provide objective spectral markers for the assisted diagnosis of electrical marks.     

Forensic oral imaging quality of hand-held dental X-ray devices: Comparison of two image receptors and two devices

Recently, different portable hand-held and battery-powered dental X-ray units have become available. Especially for forensic odontological purposes, they offer diverse advantages such as for use in disaster areas and crime-scene locations as also in autopsy rooms and mortuaries. For any application, the most important feature of these hand-held devices is the delivered image quality. The aim of this study is to evaluate the radiographic image quality acquired by two portable X-ray devices in combination with two types of image receptors and to compare the findings with the image quality of a standard intra-oral X-ray device.Eleven samples consisting of eight teeth, two dry skeletal specimens and one formalin-fixed mandible part were mounted on blocks for standardised (re)positioning. Radiological images were acquired with two hand-held (AnyRay^® 60 kVp, 0.02–4.00 mAs and NOMAD^® 60 kVp, 0.023–2.277 mAs) and one wall-mounted (MinRay^® 60/70 kVp 0.14–22.4 mAs) X-ray device combined with two image receptor systems (VistaScan^® phosphor storage plate (PSP) and SIGMA^® M CMOS Active Pixel technology sensor). The effect of X-ray source-to-object distance (SOD) was checked at 20 cm in conjunction with object to image receptor distances (OIDs) of 0.8 and 2.5 cm. For each parameter setup, the exposure times were run from low till high. An expert consent statement was achieved by agreement of four expert observers selecting the optimal images based on a developed four point quality rating system. Next, a selection of the images was assembled in a set of 198 observation screens and scored by seven observers. The observation screens were designed to compare observer scores, relations between devices, receptors and OIDs and images obtained from the different devices at equal exposure levels (mAs). All results were statistically analysed.Radiological image quality was significantly higher for phosphor plate compared with the CMOS digital receptor system (p < 0.0001). Furthermore, a significantly superior image quality was obtained for OID = 0.8 than for OID = 2.5 (p = 0.039). A significant difference in image quality between the three devices was also established (p = 0.02). The present study demonstrated the feasibility of portable X-ray systems for forensic odontological applications based on rendering optimal image quality, provided an in vitro guideline of optimal parameter settings and offered a radiological image database usable in further research.     

An investigation into the persistence of textile fibres on buried carcasses

A significant amount of research has been carried out on fibres to aid the forensic scientist in determining the significance of these when found on a victim or suspect. This work has focused on open-air environments, and as such no research has been undertaken to examine the persistence of fibres on bodies in the burial environment.Wool and cotton fibres, known to fluoresce under ultraviolet (UV) light, were transferred onto the skin of four porcine (Sus scrofa) carcasses (two carcasses per fibre type). The number of fibres transferred was recorded from images taken under UV light. The remains were subsequently placed in four burial sites and left interred for 14 days. After this period the carcasses were excavated and lightly brushed down to remove the soil layer that had adhered to the skin. Once again photography under UV light was used to record the number of fibres which persisted on the skin.Results showed that after 14 days, wool and cotton fibres remain on the surface of the buried carcasses. In no circumstance was there a total loss of fibres suggesting that in such scenarios, the likelihood of finding fibres is high but the initial number of fibres transferred would be strongly diminished. This has important implications for both the excavation protocol for buried remains and the subsequent analysis for physical evidence.