Abstract The nature of forensic geoscience Forensic geoscience may be defined as a subdiscipline of geoscience that is concerned with the application of geological and wider environmental science information and methods to investigations which may come before a court of law. The scientific boundaries of forensic geoscience are not clearly defined, and there are significant overlaps with other, related subdisciplines such as forensic archaeology (Hunter et al. 1987), forensic anthropology, forensic botany ( Hall 2002 ; Horrocks & Walsh 1998 ), forensic engineering ( Shuirman & Slosson 1992 ) and even forensic medicine and forensic pathology ( Knight 1997 ; DiMaio & DiMaio 2001 ). Forensic geoscience is concerned with all aspects of earth materials, including rocks, sediments, soil, air and water, and with a wide range of natural phenomena and processes. Since modern sediments and soil also often contain objects and particles of human origin, man-made materials such as brick, concrete, ceramics, glass and various other industrial products and raw materials are also sometimes of interest. These may be of relatively modern origin or of archaeological importance (e.g. Henderson 2002 ). Forensic geology ( Murray & Tedrow 1975, 1992 ) may be regarded as a subset of forensic geoscience and is principally concerned with studies of rocks, sediments, minerals, soils and dusts. Environmental forensics ( Morrison 2000 ; Murphy & Morrison 2002 ), on the other hand, has somewhat wider scope than forensic geoscience, with much stronger links to disciplines such as chemical engineering, and with a greater concern with such issues as groundwater contamination and air pollution modelling. Forensic geoscience is by nature

Abstract Sir Arthur Conan Doyle and Hans Gross suggested the possibility of using soil and related material as physical evidence. Edmond Locard provided the intellectual basis for the use of the evidence. High-visibility cases, such as the work of the Federal Bureau of Investigation (FBI) in the Camarena case, the laboratory of the Garda Siochana in the Lord Mountbatten case and G. Lombardi in the Aldo Moro case, contributed to the general recognition that geological evidence could make an important contribution to justice. The value of geological evidence results from the almost unlimited number of rock, mineral, soil and related kinds of material combined with our ability to use instruments that characterize these materials. Forensic examinations involve identification of earth materials, comparison of samples to determine common source, studies that aid an investigation and intelligence studies. The future will see increased use of the evidence, new automated methods of examination, improved training of those who collect samples, and research on the diversity of soils and how, when and what parts of soils are transferred during various types of contact. The microscope will remain important because it allows the examiner to find the rare and unusual particle.

Abstract A wide range of geophysical techniques is applied in forensic investigations where the target objects are frequently buried under ground and are often small in size. These include targets which are only a few centimetres in diameter but located within a large search area are often of several hectares. The application of a specific geophysical technique may be governed by the physical properties of the target object and its local surroundings. However, operational and financial costs are important. Topographical and geological variations or presence of man-made structures may hinder the application of the most cost-effective technique. Additionally, site area, logistics and weather conditions are also important factors. Generally, to overcome these difficulties it is recommended that forensic geophysics be carried out along conventional geophysical guidelines as used in civil-engineering site investigation. On occasion, departure from these conventional guidelines may be beneficial in that field survey data acquisition can be complemented by simultaneous direct invasive assessment of geophysical anomalies instead of waiting until office reporting has been completed. Three case studies are presented: one relates to a search for a buried metal target located using a scanning magnetometer with simultaneous excavation, and two relate to searches for graves and buried wooden coffins

Abstract In the UK, geophysical survey methods have been increasingly applied in the search for clandestine burials and in the elimination of land from murder enquiries as part of a broader spectrum of systematic search techniques. This paper considers recent forensic search work and stresses the general resources and intelligence needed for a successful search, and the role played by geophysics. The main emphasis, however, is to discuss the applicability of ground-penetrating radar (GPR) in grave detection and to review recent developments in software, particularly the importance of high-resolution mapping. The paper also discusses the use of image analysis of both planes through blocks of buried landscape, together with predictive modelling and the value of 3-D analysis for data manipulation.

Abstract Geophysical surveys are being increasingly applied for the detection of clandestine burials. Ground-penetrating radar has been used successfully but is not appropriate for many sites. For this reason, other techniques such as resistivity mapping are being tested. Resistivity is sensitive to many different changes in the ground that can be caused by a grave; however, the small physical extent of the target makes location extremely difficult. Other environmentally caused variations in resistivity may be of the same magnitude as those caused by a grave, and it is important to consider whether the resistivity anomaly caused by a grave can be detected over this background variation. This paper provides a summary of the method and discusses two case studies in which resistivity mapping was employed to locate a clandestine grave. The resistivity results of a survey over moorland were dominated by the thickness of the peat coverage while the resistivity of a survey in a river valley was dominated by various environmental variations, including a medieval furrow system. Both sites were eliminated from enquiries after extensive cadaver dog searches and some excavation, although it was considered that the environmentally caused resistivity variations at both sites would have made location of a grave by resistivity alone extremely difficult. However, the success of resistivity for landfill locations suggests that resistivity may be more appropriate for the location and delineation of larger features such as mass graves.

Abstract The laws of stratigraphy, developed in geology, have long been adopted for archaeological use. Archaeological excavation in the UK relies on the application of these principles to define, interpret and understand site history. The adaptation of archaeological methods to forensic settings has recently resulted in successful analysis of stratigraphy-defining complex series of events on murder burial scenes. The breadth of physical evidence that can be recovered through stratigraphic excavation is great, and that which can be lost without due attention to the buried surfaces forming an intrinsic part of the stratified deposits of a site is significant. Recent case examples demonstrate the importance of employing stratigraphical principles in the excavation and interpretation of buried cultural and natural deposits as part of multidisciplinary forensic investigation.

Abstract Colour is a fundamental characteristic of many materials, including soils and sediments, and has been much used in geological, pedological and Quaternary science research. Traditionally, colour has been described qualitatively by visual comparison with standard charts, such as the Munsell Soil Color Charts or the Geological Society of America Rock Color Chart . Instrumental colour determination has been developed and used in industry for a variety of applications, including quality testing of paints, dyes and foodstuffs. In this paper, colour theory is outlined, and the Minolta® CM-2002® hand-held spectrophotometer is tested on geological samples to investigate reproducibility, discriminatory power, and accuracy in analysis. Standard methods for calibration, presentation and testing of a variety of (often small) samples have been developed. Examples are provided for the use of the method in forensic geoscience casework.

Abstract Particle size distribution is a fundamental property of any sediment or soil, and particle size determination can provide important clues to sediment provenance. For forensic work, the particle size distribution of sometimes very small samples requires precise determination using a rapid and reliable method with a high resolution. A protocol has been developed using a Coulter™ LS230 laser granulometer, which can analyse particles in the size range 0.04 μ–2000 μ. The technique is essentially non-destructive, permitting the recovery of critical samples, and has been demonstrated to have high precision for a range of soils, sediments and powders of interest in forensic investigations.

Abstract A database of coastal dune sediments in England and Wales has been developed with potential applications in forensic investigations. Coastal dunes are popular sites for criminal-related activities, including burial of drugs, weapons and murder victims. The coastal dunes and associated areas of windblown sand in England and Wales occupy an area of approximately 200 km 2 within 112 individual identified systems. Research has been undertaken to ascertain the spatial variation in sedimentological properties of the coastal dune sediments in England and Wales. Field sediment sampling has been undertaken at each dune system. More than 1500 sediment samples have been analysed by laser diffraction to determine particle size characteristics, and more than 500 have been analysed by inductively coupled plasma atomic emission spectrometry (ICP-AES) to determine chemical composition. Two examples illustrate how the database has been used in criminal investigation.

Abstract Soil is presented as evidence as a mixture of both natural and artificial materials. ‘Unique’ particles found in soil may provide useful information to indicate the origin of the soil and, when found in soil evidence, may provide rapid discrimination between samples. Evidence in poor condition may also be examined for these diagnostic particles. This paper describes some case examples and research, involving geological particles, plant fragments and algae, in which microscopy played an important role.

Abstract Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) microanalysis are powerful techniques for forensic and wider environmental analysis of a range of materials, including rocks, sediments, soils and dusts. Methods of analysis have evolved rapidly over the past 40 years and computer-controlled, variable pressure SEMs with integrated EDX now provide the opportunity for rapid, automated analysis of large numbers of samples and particulates within individual samples. However, interpretation of the data requires care and experience on the part of the operator, and samples should always be checked by visual inspection. Early SEM work on rocks and sediments mainly used the secondary electron (SE) mode to produce topographical contrast on rough surfaces, but more recent studies have utilized the capacity of backscattered electron (BSE) imaging to image both topographical and atomic number contrast. BSE microscopy, combined with X-ray mapping, provides a rapid means of locating unusual particles and grain coatings, and of mapping their distribution, which may be of diagnostic or discriminatory importance. In the past, much attention has been given to grain surface textural features (mainly of quartz) but many such studies have suffered from a high degree of subjectivity, poor reproducibility, lack of discriminatory power, and high cost both in terms of time and money. The application of digital imaging and statistical data-processing techniques can to some extent reduce these problems but, in general, chemical characterization of particles offers a more powerful approach. This paper provides an overview of these techniques, discusses their limitations and illustrates some of the forensic and wider environmental applications.

Abstract QemSCAN is a scanning electron microscope (SEM) system, initially designed to support the mining industry by providing rapid automated quantitative mineral analyses. The system is based upon Carl Zeiss SEMs fitted with up to four light-element energy dispersive X-ray spectrometers. Representative subsamples are mounted into either resin or wax blocks and polished prior to analysis, or can be mounted onto carbon tape. During analysis, X-ray spectra are collected at a user-defined pixel spacing and are acquired very rapidly ( c. 10 ms per pixel). The measured spectra are automatically compared against a database of known spectra and a mineral or phase name is assigned to each measurement point by the QemSCAN computer software programs. In this way the near-surface qualitative elemental composition of each particle is systematically mapped, assigned to a mineral name or chemical compound/species, and digital pixel maps of each particle are created. Depending upon a range of parameters, including the particle size and the user-defined pixel spacing (which can vary between 0.20 μm and 25 μm), approximately 1000 particles, each 1–10 μm in size, can be measured per hour using a 1 μm pixel spacing. In addition to providing a qualitative elemental analysis and mineralogical or phase assignment for each particle, data relating to particle size, shape and calculated specific density are also generated. In this study, the potential application of this automated SEM system in forensic geoscience was evaluated by the analysis of: (1) a series of soil samples, and (2) a series of dust samples from an industrial complex. In both case studies, the mine-ralogy/phase composition of each sample analysed was found to be distinctive. In addition, textural data for the soil samples and particle shape data for the dust samples show that they can be clearly distinguished. Automated SEM using QemSCAN has clear potential application in the analysis of soil or other trace evidence in forensic case work.

Abstract Cosmic dust grains are the abundant, fine-grained end-member of a range of extraterrestrial materials travelling through space. These particles can impact orbiting space vehicles (e.g. satellites and the International Space Station) at velocities ranging from 10 to 72 km s −1 . Impact damage resulting from such a collision could potentially disable or limit the operational use of a spacecraft. There is great commercial interest from the satellite companies and space agencies to understand the nature and proportion of impacts that are caused by cosmic dust particles to assist in risk management studies and for protective shielding optimization. The successful recovery of any surface that has been exposed to the near-Earth environment offers an excellent opportunity to search for micrometre-scaled impact features and the associated projectile residues using scanning electron microscopy and X-ray microanalysis.

Abstract The use of scientific techniques in the investigation of archaeological sites and artefacts has a long history. These days archaeological science as a discipline has matured to the extent that well-defined questions can be answered in increasingly refined ways. In this paper consideration of specific case studies highlights the kinds of investigations that have been carried out on archaeological materials. The research projects are described in ways that show parallel approaches to more recent types of research in police forensic work. The two case studies focused on are: (1) Islamic glass production — a cross-roads in technology? (eighth to twelfth centuries ad ); (2) Ottoman Iznik pottery: the state of the art or the art of the State? (fifteenth to seventeenth centuries ad ). A range of analytical techniques has been used, including electron microprobe analysis, inductively coupled plasma atomic emission spectrometry, scanning electron microscopy and mass spectrometry. Clearly these techniques provide different (and sometimes overlapping) information which help to answer research questions. The characterization of raw materials, production processes and distribution zones of the products all form part of a holistic approach. Ideally the results should be embedded in our knowledge of past societies, just as the interpretation of police forensic work should be.

Abstract An initial survey of the advantages and disadvantages of Raman spectroscopic techniques for application to forensic crime scene analysis in a geoscience context is followed by some illustrative examples that demonstrate the potential information which can be forthcoming from Raman spectral data and molecular characterization. A range of specimens is reported, including Egyptian human mummies, ice-mummified bodies, resins and ivories; all of these can be related through a geoscience context and the potential for forensic application is indicated.

Abstract Inductively coupled plasma analytical techniques are widely used in forensic geochemistry because they can provide concentration data for a wide range of major and trace elements relatively rapidly and at reasonable cost. A pilot study was undertaken to identify the relative importance of uncertainty resulting from instrumental measurement sources and that due to the procedures used to prepare the samples initially. Three soils with a range of major and trace element concentrations were collected to permit an evaluation of uncertainty. A reference sample of demonstrated homogeneity was also prepared and analysed. Samples were prepared in replicate (five preparations) of each, and assessment made of uncertainty in the instrumental measurement alone and for replicated preparations of the same material. Small sample sizes (0.05g) were used to mimic the situation common in forensic investigation. Results show that, while instrumental variability may be an important factor during measurement, between-sample variation has a dominant effect on uncertainty in the final result. It is clear that, without replicated measurement and preparation, the uncertainty of the measured data is unknown. Thus, critical samples, on which a case might depend, must be analysed in a way that defines clearly that uncertainty.

Abstract Analysis of geochemical data has become an important tool used in forensic comparisons of soils and sediments. The combined use of inductively coupled plasma optical emission spectrometry and mass spectrometry (ICP-OES and ICP-MS) instrumentation allows the abundance of up to 50 elements to be routinely determined in small samples (typically >0.1g). However, key issues concern the extent to which analysed subsamples are representative of the parent material from which they are taken, the best means of comparing datasets for different samples, and interpretation of the significance of the results obtained. ICP measurement precision for most elements is good, but it is important to understand the degree of variation that can arise due to subsampling procedures and selective transfer mechanisms relating to forensic exhibits, as well as the extent of spatial (and sometimes temporal) variability which exists in nature. Although analysis of several different size fractions is often helpful where sufficiently large samples are available, analysis of a standardized <150μm fraction separated from a bulk sample in many cases provides adequate discrimination between samples and provides the most practical method for mass-screening of samples. Where possible, duplicate or triplicate sample preparations should be made, and several analytical determinations made on each prepared subsample. However, the additional time, cost and sample size requirements involved need to be weighed against the benefits of undertaking additional types of analysis of the samples. In order to obtain maximum information from multielement geochemical data, the dataset should be evaluated using a variety of numerical, statistical and graphical procedures. This paper discusses a number of options for such data evaluation using a simple dataset example. Casework experience and experiments have shown that, even in complex situations, multi-element geochemical data can provide very sensitive environmental indicators. However, such data should normally be used in combination with the results of other analyses when making forensic comparisons of soils and sediments.

Abstract Data from a regional soil survey in eastern England have been used to determine whether samples over the same parent material can be discriminated on the basis of both individual and multielement geochemistry. Discrimination was based on estimates of measurement uncertainty, which were calculated from the analysis of a series of duplicates and subsamples. In the multivariate analysis we estimated a covariance matrix for the two sources of uncertainty and compared this to Mahalanobis distances calculated for pairs of samples within each parent material group. For 12 of the 19 individual elements, it was possible on average to discriminate between more than 80% of the samples within parent material groups and typically between 15 and 17 of the 19 elements discriminated individual samples. In the multi-element analysis, typically more than 99.8% of samples within the same parent material group were discriminated from one another. Hence, the geochemistry of a natural soil sample, when collected and analysed according to a strict protocol, and compared to a database that adopted the same methods, could be used to help establish provenance within bedrock-derived soil types. However, there are significant differences between the nature of soil samples and the way they are collected or derived in soil surveys and forensic investigations. These questions need to be addressed thoroughly before any practical application to forensic cases in which an investigator is attempting to link a suspect to a location based on soil geochemical signatures.