MINERVA MED LEG 2007;127:73-89 Forensic geoscience and crime detection Identification, interpretation and presentation in forensic geoscience R. M. MORGAN, P. A. BULL Forensic geoscience is based upon well establi- Oxford University Centre for the Environment shed ideas and analytical techniques developed University of Oxford, Oxford, UK throughout the 20th century. Recent advances in geological and chemical analytical techni- ques have enabled, for the first time, detailed soil and sediment assay which has been taken up particularly by British scientists. A conceptual cope with the ever increasing complexities of framework for forensic geoscience is reiterated data analysis and interpretation in order for which supports the positive development in the the results to be presented in an unbiased and future of forensic geoscience, soil and sediment analyses. However, this paper also seeks to hi- clear way to both judge and jury in a court of ghlight the pitfalls encountered in recent years: law. These problems are compounded in the use of analytical techniques that are depen- forensic geoscience by additional complica- dent upon one another; the dependence on the tions in data acquisition, analysis, interpreta- exotic components of a sample, whether they tion and presentation which are individual to are representative or not; the confusion between descriptive; exclusionary and diagnostic tech- this particular, rapidly expanding, field of niques, and the failure to comprehend the re- forensic enquiry. Inspection of the post-2000 quirement to exclude rather than to match com- scientific published literature confirms the ex- parison samples. Furthermore, the use of auto- panding nature of forensic geoscience,1 but mated, computer driven, multiple-sample analy- we must ask ourselves whether this burgeon- tical machinery is questioned when there is no visual assessment by an operator included in ing of geological applications is but another the procedure. Avoiding these pitfalls and adop- false dawn in a series of false starts seen ting the philosophical framework specific to fo- throughout the 20th century. Certainly, if we do rensic geoscience will ensure a role for the ap- not learn from mistakes and do not take heed plication of forensic geoscience in the field of cri- of comments and advice given in the past, minal investigations. then this current resurgence in the use of geo- Key words: Forensic geoscience - Philosophy - science applications to forensic problems will Soil - Geologic sediment. once again fail to reach its full potential. This paper introduces the recent developments in forensic geoscience set within the context of ne of the most pressing issues in foren- problems which beset the discipline. Osic science at the present time is how to What is forensic geoscience? Address reprint requests to: R. M. Morgan, Oxford University Centre for the Environment, University of Oxford, South Parks Road, Oxford OX1 3QY, UK. Forensic geoscience is a field of enquiry E-mail: [email protected] that utilises techniques developed in the geo- Vol. 127, N. 2 MINERVA MEDICOLEGALE 73 MORGAN FORENSIC GEOSCIENCE AND CRIME DETECTION TABLE I.—Macro and micro geoforensic applications. Scale Technique Purpose Reference Macro Resistivity and electrical tomography Detecting burial sites France et al. 1992,2 Buck 2003,3 Scott and Hunter 2004 4 Electromagnetic surveying (EM) and Ground- Detecting burial sites Nobes 1999, 2000 5, 6 Penetrating Radar (GPR) GPR Detecting historic mass Davis et al. 2000,7 burial sites Chen et al. 2001 8 Plastic landmine detec- tion Forensic geomorphology (landscape interpretation) Detecting burial sites Owsley 1995 9 Physical probe Detecting buried objects Owsley 1995 9 Forensic remote sensing (aerial photography, satellite Environmental forensic Brilis et al. 2000, imagery and global positioning systems) applications 2001, 10, 11 Grip et al. 2000 12 Geographic Information System (GIS) Spatial analysis of crimi- Canter 2003, 13 nal behaviour and crimi- Zhivotovsky et al. 2001 14 nal ancestry Micro Physical characteristics of Binocular microscopy Comparison of samples Murray 2004,15 a soil/sediment sample (mineralogy) and/or assessment of the Morgan et al. 2006 16 provenance of samples. 17 X-Ray Diffraction (XRD) Brown 2006, (mineralogy) Ruffell and Wiltshire 2004 18 QemSCAN Pirrie et al. 2004 19 Quartz grain surface Bull and Morgan 2006 20 texture analysis Particle size analysis Morgan and Bull in press.21 Colour Janssen et al. 1983,22 Sugita and Marumo 1996, 23 Junger 1996.24 Chemical characteristics ICP-MSa and ICP-AESb Comparison of samples Rawlins and Cave 2004,25 of a soil/sediment sam- (elemental chemistry) and/or assessment of the Jarvis et al. 2004 26 ple AAS/Dionexc (elemental provenance of samples. Morgan et al. 2006, 16 chemistry) Bull et al. 2006 27 FTIRd (organic content) Cox et al. 2000 28 Biological characteristics Pollen Comparison of samples Bruce and Dettmann of a soil/sediment sam- and/or assessment of the 1996,29 Bryant et al. 1996, ple provenance of samples. 30 Szibor et al. 1998,31 Eyring 1996,32 Horrocks et al. 1998,33 Horrocks and Walsh 1998, 1999,34, 35 Horrocks 2004,36 Miller Coyle 2005,37 Mildenhall et al. 2006,38 Montali et al. 2006,39 Wiltshire 2006.40 Bacterial DNA Horswell et al. 2002 41 Plant wax signatures Dawson et al. 2003 42 a ICP-MS: Inductively Coupled Plasma-Mass Spectrometry; b ICP-AES: Inductively Coupled Atomic Emission Spectroscopy; c AAS: Atomic absorption Spectrometry; d FTIR: Fourier Transform Infra Red spectroscopy. 74 MINERVA MEDICOLEGALE Giugno 2007 FORENSIC GEOSCIENCE AND CRIME DETECTION MORGAN sciences (such as geology, geomorphology, anthropogenic components such as glass, botany, biology and statistics) for application paint fragments, metallic particles etc. Thus, to civil and criminal judicial proceedings. a sample of soil/sediment recovered from Forensic geoscience may include both macro clothing, a vehicle or a crime scene has “…a and micro-scale applications 2-42 (Table I). large, almost limitless number of characteristics The macro-scale applications of forensic which make it unique but which relate to the geoscience have been reviewed elsewhere, 43 climate, geology or land use of the site from thus this review considers specifically the which the soil was derived”,54 indeed there role of forensic geoscience in crime detection are “…an almost unlimited number of soil at the micro-scale. At this micro-scale the varieties and soils change rapidly from place geo-forensic application falls within the aegis to place even over short distances”.55 The va- of trace evidence analysis, which has devel- lue of soil/sediment analysis in providing oped its own principles and practice since useful evidence in forensic enquiries lies with the utilisation of the microscope in forensic the ability of the forensic practitioner to ma- enquiry in the 19th century. ke comparisons between soil/sediment The well established principles and pro- samples and, on occasion, to infer prove- tocols of trace evidence studies as applied nance. to hair, paint fragments, glass particulates, fi- The concept of facies and sedimentary bres, metals etc. have now amalgamated units is a keystone to the analysis of soils within them the more recent developments of and sediments in forensic enquiry. A “…sed- forensic geoscience (incorporating studies of imentary facies is defined as any aerially re- soils and minerals, pollen and micro-fossils). stricted part of a designated stratigraphic unit Whilst such a grouping is seemingly logical, which exhibits characteristics significantly the well developed protocols of the former different from those of other parts of the group of trace evidence analyses do not take unit”.56 It is, in other words, distinctive as a re- into account the nature, philosophy and prac- sult of the similarities within the unit and its tice specific to these geoforensic studies. distinctiveness from other units. Accordingly, Conversely, the geoforensic trace materials it follows that facies are discrete and, there- are often analysed and interpreted by a foren- fore, restricted in extent both stratigraphical- sic geoscientist in a totally obverse manner in ly and geographically. 57 Thus there is a dis- comparison to that of the properly estab- cernable difference between sedimentary lished trace material analyst. units in the spatial dimension. The most im- Geoforensic science has relevance to oth- portant application of this, therefore, is that er forensic disciplines. Medical applications sediments are not to be found in a melange include the identification of trace materials ad- of indiscrete units but rather the inter-rela- hering to bodies, under fingernails, in nasal tionships of sedimentary environments, and passages, in lung and stomach contents and hence of facies, are not chaotic or random, also in the blood system (diatoms;44-48 but subject to controls such as climate, tec- pollen;49, 50 entomology 51). tonics and geological setting.58 Therefore, soils and sediments have been argued to pos- Soil/sediment as geoforensic evidence sess the “…clearest expressions of landscape complexity”, their “…spatial variability is high It is gradually being recognised that and intricate over short distances, whether “…much potentially useful information is in profile or in plan”.59 As no two similar en- locked up in even small amounts of soil” 52 vironments are exactly identical,60 this char- and this can be attributed not only to its acteristic of soils and sediments