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1.
Sci Justice ; 62(2): 129-136, 2022 03.
Article in English | MEDLINE | ID: mdl-35277225

ABSTRACT

Empirical studies evaluating the conditions under which the transfer of forensic materials occurs can provide contextual information and offer insight into how that material may have been transferred in a given scenario. Here, a reductionist approach was taken to assess the impact of force, time, and rotation on the transfer of an explosive compound. An Instron ElectroPuls E3000 material testing instrument was used to bring porous and non-porous surfaces adulterated with an ammonium nitrate into direct contact with a human skin analogue, controlling for the force of contact, duration of contact, and rotation applied during contact. Quantifiable amounts of ammonium nitrate were recovered from all of the recipient surfaces demonstrating that ammonium nitrate is readily transferred from one surface to another, even when contact occurs for a short duration with a relatively low force. More particulates were transferred from non-porous surfaces onto the human skin analogue, but the amount of ammonium nitrate transferred did not depend upon the force of contact, duration of contact, or the amount of rotation applied. However, when contact occurred and involved rotation, a greater transfer of ammonium nitrate was observed, compared to those contacts occurring without rotation being applied. This approach complements more commonly-used holistic experiments that test multiple interacting variables in a realistic setting by isolating these variables, allowing them to be examined individually. This can be utilised to better understand the individual impact that specific variables have on the transfer of trace evidence in relevant crime reconstruction contexts.


Subject(s)
Explosive Agents , Nitrates , Forensic Medicine , Humans , Rotation
2.
Sci Justice ; 62(2): 221-228, 2022 03.
Article in English | MEDLINE | ID: mdl-35277236

ABSTRACT

It is well established that a large proportion of paper banknotes in circulation contain traces of cocaine. Being able to discriminate between the innocent transfer of illicit drug particles acquired through everyday interactions with surfaces such as banknotes, as opposed to transfer resulting from criminal activities can provide valuable intelligence that can inform an investigation. With many countries adopting polymer banknotes as legal tender, it is important to consider the transfer of cocaine from these surfaces as well as the retention of these particulates on polymer banknotes for evaluative interpretation in crime reconstruction. This comparison study assessed three contact variables (force, time, and rotation) on the transfer of cocaine particulates from paper and polymer banknotes onto a human skin proxy. The persistence of cocaine particulates was assessed through a realistic scenario which mimicked a cash transaction. Quantifiable amounts of cocaine were transferred onto the human skin proxy across all of the contacts assessed, with a greater transfer observed with contacts involving polymer banknotes and those contacts which involved rotation. Following extensive handling, cocaine persisted on both banknote types, with paper banknotes retaining larger amounts of cocaine than polymer banknotes. These findings show that cocaine can persist on both paper and polymer banknotes for extended periods of time following handling and is therefore available for transfer. This transfer then readily occurs, even when contact is brief and involves relatively small forces. A key distinction between the banknote types was that cocaine particulates are more likely to transfer from polymer banknotes due to the lower retention rate of particulates on this surface. Such insights can aid in evaluating the relevance of illicit drug particles identified on items or persons of interest in crime reconstruction approaches.


Subject(s)
Cocaine , Illicit Drugs , Humans , Paper , Polymers
3.
Forensic Sci Int ; 326: 110897, 2021 Jul 04.
Article in English | MEDLINE | ID: mdl-34411937

ABSTRACT

Diatoms are a useful form of environmental trace evidence, yielding a circumstantial link between persons and scenes of forensic interest. A developing empirical research base has sought to understand those factors affecting the transfer and persistence of freshwater diatoms on clothing and footwear surfaces. Although an initial study has demonstrated that diatoms can persist on clothing following weeks of wear, no previous research has explored the temporal dynamics of a persistent species assemblage over timescales pertinent to forensic investigations. This study therefore aimed to determine if: (1) valve morphology (size and shape) influences diatom persistence, (2) the relative abundance of taxa within an assemblage affects retention, and (3) a persistent diatom assemblage retrieved from clothing after one month can reliably be compared to the site of initial transfer. To build on previous research findings which highlighted the impact of substrate and environmental seasonality on diatom transfer and persistence, here, nine clothing materials were tested in spring before a seasonal comparison in the winter. Fabric swatches were immersed in a freshwater river, worn attached to clothing, and subsamples retrieved at regular intervals (hours, days, weeks) up to one month post-immersion. Diatoms were extracted using a H2O2 technique and analysed via microscopy. The results indicated that smaller diatoms (< 10 µm) are retained in significantly greater abundance, with no statistically significant difference between centric and pennate diatom loss over time. Although a persistent species assemblage was relatively stable over the one month of wear, significant differences were identified between clothing substrate in the spring and between the seasonal samples. The most abundant environmental taxa were consistently identified in the forensic samples, with greater variability attributed to the retention of relatively less common species. The findings suggest that, despite a loss in the abundance and species-richness of diatoms retrieved from clothing over time, a persistent assemblage may provide a useful circumstantial link to the site of initial transfer. The complex relationships between clothing type, environmental seasonality, and time since wear on retention, emphasise the need for diatom trace evidence to be carefully interpreted within an exclusionary framework, and the significance of any casework findings to be determined with reference to empirical evidence bases.

4.
Forensic Sci Int ; 325: 110898, 2021 Aug.
Article in English | MEDLINE | ID: mdl-34247142

ABSTRACT

Freshwater diatoms offer valuable circumstantial forensic indicators, with a growing empirical research base aiming to identify and understand some of the spatial and temporal factors affecting their validity as trace evidence. Previous studies demonstrated that recipient surface characteristics, environmental variability, and individual species traits influence the initial transfer of freshwater diatoms to clothing. However, no previous research has sought to consider the impact of these and other variables on the persistence of transferred diatoms over investigative timescales. Therefore, this study aimed to identify and explore diatom retention dynamics on clothing following wear over time (hours to weeks). A series of experiments were designed to examine the impact of clothing material, seasonality, and time since wear (persistence interval) on the total number and species-richness of diatoms recovered and their relative retention (%) over time. Nine clothing swatches were immersed in a freshwater environment and then worn for one month in the spring. Subsamples were retrieved at regular intervals (e.g. 30 mins, 1 h, 8 h, 24 h) up to one month, diatoms were extracted using a H2O2 method, and examined microscopically. Three clothing materials were subject to the same experiment in the winter to generate a seasonal comparison. The results broadly identified three stages of diatom persistence on clothing - rapid initial loss, variable intermediate decay, and sustained long-term presence. Clothing material significantly impacted the number of diatoms recovered and retention dynamics over time, with complex interactions identified with seasonality. Although fewer diatoms were recovered in the winter, overall retention trends were consistent at the different times of year. The findings demonstrate that diatoms can be recovered from clothing, even weeks or months after an initial transfer, yielding a useful environmental trace indicator for forensic reconstructions over investigative timescales. The impact of clothing material and seasonality on persistence identified cotton, acrylic, and viscose clothing as the most reliable temporal repository of diatom trace evidence, with a more abundant forensic assemblage available for forensic comparisons in the spring.


Subject(s)
Clothing , Diatoms , Fresh Water , Forensic Sciences , Humans , Seasons , Specimen Handling
5.
Sci Justice ; 60(6): 531-537, 2020 11.
Article in English | MEDLINE | ID: mdl-33077036

ABSTRACT

Forensic scientists must be able to recover traces of any original explosive materials not consumed in the detonation, in a careful controlled manner to aid a crime reconstruction. In current sampling techniques, the collection efficiency of post-blast residue is highly variable and often dependent on the swabbing materials and solvent systems used. To address these method limitations, this study presents a gelatine-based sampling medium and assesses its capabilities for the collection of ammonium nitrate. Common surfaces were spotted with a known concentration of ammonium nitrate, the unset gel applied, allowed to set, and then peeled from the surface. The gel was dissolved, and solid phase extraction employed to isolate the target explosive compound and remove the constituents of the gel. The eluate was concentrated and subsequently analysed and quantified. Overall, the gel formulation was able to collect ammonium nitrate from all of the test surfaces, with recoveries ranging from 0.1% to 61.7%. This study presents a gelatine-based formulation that has the potential to become a valuable asset in the forensic tool kit for the collection of explosive traces. A key attribute of the gel is that it offers an alternative recovery tool to conventional swabbing and solvent extraction methods.


Subject(s)
Explosive Agents , Explosive Agents/analysis , Humans , Nitrates/analysis , Solvents
6.
Sci Justice ; 60(4): 313-336, 2020 07.
Article in English | MEDLINE | ID: mdl-32650934

ABSTRACT

This study provides a set of tools for conceptualising, evaluating and communicating uncertainty in forensic science. Given that the concept of uncertainty is one that transcends disciplinary boundaries, an interdisciplinary configurative review was carried out incorporating the disciplines of medicine, environmental science and economics, in order to identify common themes which could have valuable applications to the discipline of forensic science. Critical Interpretive Synthesis was used to develop sub-synthetic and synthetic constructs which interpreted and synthesised the underlying evidence and codes. This study provides three toolkits, one each for conceptualisation, evaluation and communication. The study identified an underlying theme concerning the obstacles that would need to be overcome for the effective application of these toolkits and achieving effective conceptualisation, evaluation and communication of uncertainty in forensic science to lay-stakeholders. These toolkits offer a starting point for developing the conversation for achieving greater transparency in the communication of uncertainty. They also have the potential to offer stakeholders enhanced understanding of the nuances and limitations of forensic science evidence and enable more transparent evaluation and scrutiny of the reliability, relevance and probative value of forensic materials in a crime reconstruction.


Subject(s)
Communication , Forensic Sciences , Crime , Humans , Reproducibility of Results , Uncertainty
7.
Sci Justice ; 59(3): 292-305, 2019 05.
Article in English | MEDLINE | ID: mdl-31054818

ABSTRACT

Environmental indicators are increasingly sought and analysed in a range of forensic reconstructions. Although the majority of casework and research studies are concerned with the criminal investigation of terrestrial habitats (soils, sediments, plants etc.), freshwater environments are also frequently encountered as crime scenes. As such, microalgae, particularly diatoms, may provide useful circumstantial trace evidence following their transfer to a victim or perpetrator. Diatom analysis is a relatively underused technique in forensic ecology, although an increased empirical research focus is beginning to recognise the evidential value of a transferred assemblage. This study aimed to examine three of the spatial and temporal variables known to influence the extent of an initial transfer of trace particulates, within the context of freshwater diatoms to clothing. A series of experiments were designed to consider the impact of recipient surface characteristics (clothing type), source environment conditions (seasonality), and morphological (type of diatom) variability, on the total number (no. per cm2) and species richness (total no. sp.) of an evidential diatom sample recovered from clothing. Nine commonly used clothing materials were immersed in a freshwater river at three times of year - the early and late spring and in the winter. Diatoms were recovered using a H2O2 extraction technique and examined microscopically. The results demonstrated that diatom transfer to clothing varies significantly, with a greater abundance and a higher species richness transferred to coarse woven surfaces including acrylic, linen, and viscose. Significantly fewer diatoms were transferred to clothing in the winter, in line with seasonal fluctuations in the source environment diatom community. Furthermore, variation in the relative abundance of particular diatom species was identified between clothing types, provisionally suggesting that morphological characteristics may also support or limit the transfer of material. These findings highlight that, although clothing may offer a valuable repository of freshwater diatom trace evidence, the interpretation of evidential material should be approached within an exclusionary framework. Thus, empirical data has been generated to develop evidence bases within forensic ecology, demonstrating some of the spatial and temporal factors which may contribute to or limit the transfer of evidence.


Subject(s)
Clothing , Diatoms/classification , Diatoms/isolation & purification , Spatio-Temporal Analysis , Forensic Sciences/methods , Fresh Water/analysis , Microscopy/methods , Seasons
8.
Forensic Sci Int Synerg ; 1: 239-242, 2019.
Article in English | MEDLINE | ID: mdl-32411976

ABSTRACT

There is growing consensus that there is a crisis in forensic science at the global scale. Whilst restricted resources are clearly part of the root causes of the crisis, a contested identity of forensic science is also a significant factor. A consensus is needed on the identity of forensic science that encompasses what forensic science 'is', and critically, what it is 'for'. A consistent and cogent identity that is developed collaboratively and accepted across the entire justice system is critical for establishing the different attributes of the crisis and being able to articulate effective solutions. The degree to which forensic science is considered to be a coherent, interdisciplinary yet unified discipline will determine how forensic science develops, the challenges it is able to address, and how successful it will be in overcoming the current crisis.

9.
Forensic Sci Int Synerg ; 1: 243-252, 2019.
Article in English | MEDLINE | ID: mdl-32411977

ABSTRACT

This study presents analysis of forensic science research funded by UK Research and Innovation (UKRI) research councils (2009-2018), representing 150 projects with a cumulative value of £56.1 m (0.01% of the total UKRI budget over this time period). The findings indicate that dedicated forensic science funding represents only 46.0% of the projects included in the dataset. Research focussed on developing technological outputs represented 69.5% of the total funding (£37.2 m) in comparison to foundational research which represented 19.2% (£10.7 m). Traditional forensic science evidence types such as fingerprints and DNA received 1.3% and 5.1% of the total funding respectively, in comparison to digital and cyber projects which received 25.7%. These data offer insight into the scale of the funding crisis in forensic science in the UK, and the need to increase the resources available, to develop ways of articulating value and to ensure that both technological and foundational research are enabled.

10.
Forensic Sci Int ; 292: e10-e12, 2018 Nov.
Article in English | MEDLINE | ID: mdl-30249530

ABSTRACT

Forensic science faces many challenges, some high profile and others that are less visible. It is argued that a holistic understanding of the complex matrix of forensic science is critical to robust and transparent forensic reconstruction approaches. This paper explores the value of incorporating the contrasting approaches to complexity of the 'hedgehog' and the 'fox', by illustrating their comparative strengths. The value of such collaboration in the context of a holistic understanding of the complex interactions that exist within forensic science, offers insights for developing approaches that can be taken to address the visible and less visible challenges at their root cause.

11.
Forensic Sci Int ; 288: 310-326, 2018 Jul.
Article in English | MEDLINE | ID: mdl-29778501

ABSTRACT

There is a need to develop a wider empirical research base to expand the scope for utilising the organic fraction of soil in forensic geoscience, and to demonstrate the capability of the analytical techniques used in forensic geoscience to discriminate samples at close proximity locations. The determination of wax markers from soil samples by GC analysis has been used extensively in court and is known to be effective in discriminating samples from different land use types. A new HPLC method for the analysis of the organic fraction of forensic sediment samples has also been shown recently to add value in conjunction with existing inorganic techniques for the discrimination of samples derived from close proximity locations. This study compares the ability of these two organic techniques to discriminate samples derived from close proximity locations and finds the GC technique to provide good discrimination at this scale, providing quantification of known compounds, whilst the HPLC technique offered a shorter and simpler sample preparation method and provided very good discrimination between groups of samples of different provenance in most cases. The use of both data sets together gave further improved accuracy rates in some cases, suggesting that a combined organic approach can provide added benefits in certain case scenarios and crime reconstruction contexts.

12.
Sci Justice ; 57(6): 460-467, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29173460

ABSTRACT

This paper builds on the FoRTE conceptual model presented in part I to address the forms of knowledge that are integral to the four components of the model. Articulating the different forms of knowledge within effective forensic reconstructions is valuable. It enables a nuanced approach to the development and use of evidence bases to underpin decision-making at every stage of a forensic reconstruction by enabling transparency in the reporting of inferences. It also enables appropriate methods to be developed to ensure quality and validity. It is recognised that the domains of practice, research, and policy/law intersect to form the nexus where forensic science is situated. Each domain has a distinctive infrastructure that influences the production and application of different forms of knowledge in forensic science. The channels that can enable the interaction between these domains, enhance the impact of research in theory and practice, increase access to research findings, and support quality are presented. The particular strengths within the different domains to deliver problem solving forensic reconstructions are thereby identified and articulated. It is argued that a conceptual understanding of forensic reconstruction that draws on the full range of both explicit and tacit forms of knowledge, and incorporates the strengths of the different domains pertinent to forensic science, offers a pathway to harness the full value of trace evidence for context sensitive, problem-solving forensic applications.

13.
Sci Justice ; 57(6): 455-459, 2017 Nov.
Article in English | MEDLINE | ID: mdl-29173459

ABSTRACT

There has been a call for forensic science to actively return to the approach of scientific endeavour. The importance of incorporating an awareness of the requirements of the law in its broadest sense, and embedding research into both practice and policy within forensic science, is arguably critical to achieving such an endeavour. This paper presents a conceptual model (FoRTE) that outlines the holistic nature of trace evidence in the 'endeavour' of forensic reconstruction. This model offers insights into the different components intrinsic to transparent, reproducible and robust reconstructions in forensic science. The importance of situating evidence within the whole forensic science process (from crime scene to court), of developing evidence bases to underpin each stage, of frameworks that offer insights to the interaction of different lines of evidence, and the role of expertise in decision making are presented and their interactions identified. It is argued that such a conceptual model has value in identifying the future steps for harnessing the value of trace evidence in forensic reconstruction. It also highlights that there is a need to develop a nuanced approach to reconstructions that incorporates both empirical evidence bases and expertise. A conceptual understanding has the potential to ensure that the endeavour of forensic reconstruction has its roots in 'problem-solving' science, and can offer transparency and clarity in the conclusions and inferences drawn from trace evidence, thereby enabling the value of trace evidence to be realised in investigations and the courts.

14.
Sci Justice ; 57(5): 349-360, 2017 Sep.
Article in English | MEDLINE | ID: mdl-28889864

ABSTRACT

In recent years there has been growing interest in environmental forms of trace evidence, and ecological trace evidence collected from footwear has proved valuable within casework. Simultaneously, there has been growing awareness of the need for empirical experimentation to underpin forensic inferences. Diatoms are unicellular algae, and each cell (or 'frustule') consists of two valves which are made of silica, a robust material that favours their preservation both in sediments and within forensic scenarios. A series of experiments were carried out to investigate the transfer and persistence of diatoms upon common footwear materials, a recipient surface that has historically been overlooked by studies of persistence. The effectiveness of two novel extraction techniques (jet rinsing, and heating and agitation with distilled water) was compared to the established extraction technique of hydrogen peroxide digestion, for a suite of five common footwear materials: canvas, leather, and 'suede' (representing upper materials), and rubber and polyurethane (representing sole materials). It was observed that the novel extraction technique of heating and agitation with distilled water did not extract fewer diatom valves, or cause increased fragmentation of valves, when compared to peroxide digestion, suggesting that the method may be viable where potentially hazardous chemical reactions may be encountered with the peroxide digestion method. Valves could be extracted from all five footwear materials after 3min of immersion, and more valves were extracted from the rougher, woven upper materials than the smoother sole materials. Canvas yielded the most valves (a mean of 2511/cm2) and polyurethane the fewest (a mean of 15/cm2). The persistence of diatoms on the three upper materials was addressed with a preliminary pilot investigation, with ten intervals sampled between 0 and 168h. Valves were seen to persist in detectable quantities after 168h on all three upper materials. However, some samples produced slides with no valves, and the earliest time after which no diatom valves were found was 4h after the transfer. Analysis of the particle size distributions over time, by image analysis, suggests that the retention of diatoms may be size-selective; after 168h, no particles larger than 200µm2 could be found on the samples of canvas, and >95% of the particles on the samples of suede were less than or equal to 200µm2. A pilot investigation into the effects of immersion interval was carried out upon samples of canvas. Greater numbers of valves were extracted from the samples with longer immersion intervals, but even after 30s, >500 valves could be recovered per cm2, suggesting that footwear may be sampled for diatoms even if the contact with a water body may have been brief. These findings indicate that, if the variability within and between experimental runs can be addressed, there is significant potential for diatoms to be incorporated into the trace analysis of footwear and assist forensic reconstructions.


Subject(s)
Diatoms , Fresh Water , Shoes , Specimen Handling/methods , Diatoms/isolation & purification , Forensic Sciences , Humans , Immersion
15.
Forensic Sci Int ; 272: 127-141, 2017 Mar.
Article in English | MEDLINE | ID: mdl-28152441

ABSTRACT

Soil is a highly transferable source of trace physical material that is both persistent in the environment and varied in composition. This inherent variability can provide useful information to determine the geographical origin of a questioned sample or when comparing and excluding samples, since the composition of soil is dependent on geographical factors such as climate, bedrock geology and land use. Previous studies have limited forensic relevance due to the requirement for large sample amounts and unrealistic differences between the land use and geographical location of the sample sites. In addition the philosophical differences between the disciplines of earth sciences, for which most analytical techniques have been designed, and forensic sciences, particularly with regard to sample preparation and data interpretation have not been fully considered. This study presents an enhanced technique for the analysis of organic components of geoforensic samples by improving the sample preparation and data analysis strategies used in previous research into the analysis of soil samples by high performance liquid chromatography (HPLC). This study provides two alternative sets of marker peaks to generate HPLC profiles which allow both easy visual comparison of samples and the correct assignment of 100% of the samples to their location of origin when discriminating between locations of interest in multivariate statistical analyses. This technique thereby offers an independent form of analysis that is complementary to inorganic geoforensic techniques and offers an easily accessible method for discriminating between close proximity forensically relevant locations.

16.
Sci Justice ; 54(4): 262-6, 2014 Jul.
Article in English | MEDLINE | ID: mdl-25002043

ABSTRACT

Bloodstains on fabrics such as clothing, soft furnishings or carpets are often encountered in casework. These stains often have a distinctive morphology that includes satellite stains, thought to be a highly sensitive feature that is a function of surface roughness. This study presents the findings of experimental studies conducted with proxy blood on two fabrics, similar in labeled composition, to assess the influence of fabric type on satellite stain generation. The morphology of proxy blood stains on the two fabric types were found to be statistically distinguishable from one another, with the volume of satellite stains generated being dependent upon the surface roughness of the fabric. These findings provide an initial step that illustrates the viability of providing an empirical evidence base for the interpretation of satellite stains in forensic blood pattern analysis (BPA).


Subject(s)
Blood Stains , Textiles , Data Interpretation, Statistical , Humans , Microscopy, Atomic Force , Microscopy, Electron, Scanning , Surface Properties
17.
Sci Justice ; 54(2): 141-5, 2014 Mar.
Article in English | MEDLINE | ID: mdl-24630324

ABSTRACT

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 0.5min and 1440min (24h). It was possible to identify all three pollen types after 30min of exposure to 400°C, and after shorter time frames the threshold for successful identification was 700°C after 0.5min for all pollen types tested and 500°C for Daffodil and Lily after 5min of heat exposure. Over longer time periods (18h (1080min)) 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.


Subject(s)
Automobiles , Fires , Pollen , Forensic Sciences , Hot Temperature , Lilium , Narcissus , Time Factors , Tulipa
18.
Sci Justice ; 54(1): 49-56, 2014 Jan.
Article in English | MEDLINE | ID: mdl-24438777

ABSTRACT

This paper presents two experimental studies that deal with the spatial and temporal distribution of pollen grains within a room of a domestic dwelling. The findings concur with the preliminary work of Morgan et al. [1] and provide greater detail as to the behaviour of pollen grains within indoor locations that are pertinent for forensic investigations. The spatial distribution of pollen in a room exhibits strong distance decay trends, with the majority of pollen recovered within 0.8m of its source. The pollen was found to persist in increasing quantities during the time the flowers were in the room. This study also shows that 20days after the flowers were removed, 25-32% of the original pollen was still present within the room. The influence of disturbance was investigated and whilst areas of high disturbance were found to retain less pollen than undisturbed locations, the influence of the proximity to source was a more dominant factor. These findings have significant implications for forensic investigation protocols, particularly the collection and interpretation phases of trace evidence analysis. The distribution of pollen around a room ensures that viable sources of trace pollen are available for transfer if contact is made between a location in the room and a suspect. The persistence of pollen many days after the flowers have been removed from a room indicates that many rooms in domestic dwellings will have distinctive assemblages that reflect the history of the flowers that have been displayed within that room in the past, and that these assemblages will persist and therefore be available for transfer. These preliminary findings indicate that investigation by forensic palynology in indoor domestic settings may well be an underutilised technique that has the potential to provide accurate and valuable intelligence and evidence for forensic enquiry.


Subject(s)
Pollen , Forensic Sciences/methods , Lilium , Specimen Handling
19.
Sci Justice ; 53(4): 375-84, 2013 Dec.
Article in English | MEDLINE | ID: mdl-24188338

ABSTRACT

Three experiments were undertaken to establish the potential for forensic palynological analysis in cases of suspected document fraud. The first study tested 6 different types of paper and 9 different types of ink (n=54) and it was established that the best retainer of particulates (in this case a proxy was used in the form of UV powder) was medium biro ink and Wove and Connoisseur paper. It was found that for the different paper types 42-52% of the particulates collected were found in the ink and thus both the paper and the ink are potentially valuable sources of trace evidence in a forensic investigation. The second study sought to address the differences in the spatial distribution of particulates on documents when writing took place before or after the paper was treated with UV particulates. Ninety-six observations were made for each piece of paper tested and it was found that when the writing took place after the particulates were applied to the paper; more particulates were retained on the paper in contrast to when the writing took place before the particulate treatment. The spatial distribution of particulates was also affected, with particulates being retained in the folds of the paper when the writing took place before particulate treatment in contrast to a more erratic pattern that emerged due to the pressure of the hand of the writer when the writing took place after the particulate treatment. The third study utilised lily (Lilium) pollen grains and the findings broadly concurred with the second study. The main difference identified was when the writing took place before the particulates were applied; when UV powder was used the particulates were retained in the folds of the paper whereas this pattern was not seen to the same degree when pollen grains were used due to their 'stickier' nature. Envelopes and the pen nibs were also found to be rich sources of pollen grains after the experiments were undertaken. These studies have implications for the application of forensic palynology in cases of suspected document fraud. Pollen grains may well be present, and their analysis has the potential to reveal not only the timing of the generation of the document, but the spatial trends revealed indicate that it may well be possible to establish the sequence of significant events for forensic reconstruction. As such forensic palynology is demonstrated to have great potential in aiding forensic investigations, and is as yet an under-utilised form of trace evidence.

20.
Forensic Sci Int ; 223(1-3): 245-55, 2012 Nov 30.
Article in English | MEDLINE | ID: mdl-23088825

ABSTRACT

This paper presents a study of quartz sand grain surface textures using atomic force microscopy (AFM) to image the surface. Until now scanning electron microscopy (SEM) has provided the primary technique used in the forensic surface texture analysis of quartz sand grains as a means of establishing the provenance of the grains for forensic reconstructions. The ability to independently corroborate the grain type classifications is desirable and provides additional weight to the findings of SEM analysis of the textures of quartz grains identified in forensic soil/sediment samples. AFM offers a quantitative means of analysis that complements SEM examination, and is a non-destructive technique that requires no sample preparation prior to scanning. It therefore has great potential to be used for forensic analysis where sample preservation is highly valuable. By taking quantitative topography scans, it is possible to produce 3D representations of microscopic surface textures and diagnostic features for examination. Furthermore, various empirical measures can be obtained from analysing the topography scans, including arithmetic average roughness, root-mean-square surface roughness, skewness, kurtosis, and multiple gaussian fits to height distributions. These empirical measures, combined with qualitative examination of the surfaces can help to discriminate between grain types and provide independent analysis that can corroborate the morphological grain typing based on the surface textures assigned using SEM. Furthermore, the findings from this study also demonstrate that quartz sand grain surfaces exhibit a statistically self-similar fractal nature that remains unchanged across scales. This indicates the potential for a further quantitative measure that could be utilised in the discrimination of quartz grains based on their provenance for forensic investigations.

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