The retrieval of fingerprint friction ridge detail from elephant ivory using reduced-scale magnetic and non-magnetic powdering materials

doi:10.1016/j.scijus.2015.10.003

Science & Justice

Volume 56, Issue 1, January 2016, Pages 1-8

https://doi.org/10.1016/j.scijus.2015.10.003 Get rights and content

Highlights

•
Reduced scale magnetic powders outperformed conventional powders for mark enhancement on seized elephant ivory.
•
The effect of fingermark age on ivory significantly affected enhancement success.
•
Usable marks were still recovered after 28 days, but the best results were obtained within 7 days.
•
No improvement in mark quality using CNA enhancement or when used in sequence with powders

Abstract

An evaluation of reduced-size particle powdering methods for the recovery of usable fingermark ridge detail from elephant ivory is presented herein for the first time as a practical and cost-effective tool in forensic analysis. Of two reduced-size powder material types tested, powders with particle sizes ≤ 40 μm offered better chances of recovering ridge detail from unpolished ivory in comparison to a conventional powder material. The quality of developed ridge detail of these powders was also assessed for comparison and automated search suitability. Powder materials and the enhanced ridge detail on ivory were analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy and interactions between their constituents and the ivory discussed. The effect of ageing on the quality of ridge detail recovered showed that the best quality was obtained within 1 week. However, some ridge detail could still be developed up to 28 days after deposition. Cyanoacrylate and fluorescently-labelled cyanoacrylate fuming of ridge detail on ivory was explored and was less effective than reduced-scale powdering in general. This research contributes to the understanding and potential application of smaller scale powdering materials for the development of ridge detail on hard, semi-porous biological material typically seized in wildlife-related crimes.

Graphical abstract

Introduction

The illegal procurement and trade of elephant ivory recently reached its 16-year high in 2011. The latest figures generated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) under the Monitoring the Illegal Killing of Elephants (MIKE) programme, estimate 22,000 elephants were illegally killed in Africa alone in 2012. In 2011, the mortality estimate via illegal routes was 25,000 animals, and with potentially increased estimates expected for 2013, this suggests that such activity remains critically high [1].

There is an increased demand for ivory, particularly across Asia. The legitimate trade of ivory in countries where elephants are indigenous is often used as a means to maintain economic stability and also perhaps paradoxically to fund conservation projects. However, the sector has become increasingly populated by major organized crime syndicates [2], which promote, amongst others, corruption, terrorism, slavery and the trafficking of weapons and drugs. Unfortunately, the lucrative nature of this market seems to outweigh the risk of prosecution. Several tonnes of raw ivory are now seized on an annual basis globally [3], [4]. Lessening of the global trade restrictions has made it easier to transport large amounts of contraband around the world. It is a logical assumption that with the extensive variety of forensic tools now available that more effort would be invested into more effectively implementing existing techniques. Unfortunately this does not appear to be the case for fingermarks. Retrieval of ridge detail or latent fingermarks is rarely considered when ivory or ivory-containing items are seized. There are many reasons why an examination is not conducted. Not least are the challenges in developing ridge detail on this type of material. When a suitably receptive surface is touched by an area of the friction ridge skin (e.g., the undersides of the hands, fingers and soles of the feet), an impression of the ridge detail, is left behind on the surface. The texture, colour and porosity of the substrate surface assist in determining the most appropriate development method, but there are many factors that influence their effectiveness. To the best of our knowledge, only one relevant scientific paper has been published on the detection of latent fingermarks on African elephant (Loxodonta africana) ivory in the past thirteen years [5]. In this work, Azoury et al. found that latent fingermarks on ivory were unstable and did not persist for periods of up to two weeks. This mark instability is to some extent due to the complex physical and chemical structure of the ivory. These authors evaluated a number of widely used development techniques, including powders, small particle reagents (SPR), cyanoacrylate fuming (using a range of dyes) and vacuum metal deposition (VMD). The selected methods, except VMD, performed satisfactorily for fresh fingermark deposits, but only a sequential treatment procedure using cyanoacrylate and black magnetic powder developed any depositions after two weeks. An in-depth assessment of the quality of ridge detail for successful search and/or comparison was not presented as part of this work. It is now critical to extend efforts towards a more comprehensive assessment of fingerprint development on ivory-based materials.

One of the oldest, simplest, cost effective and most commonly used technique for the development of latent ridge detail is via contrasting powders. The preferential adherence of a fine powder to a range of components within the latent deposit enables sufficient contrast between the deposit and the underlying surface to be able to visualise the friction ridge detail [6], [7]. This development method continues to be the focus of on-going research and application in other areas of wildlife-related crime [8]. Where successful, it could present a viable and sustainable approach to the retrieval of forensic evidence in situ and especially at source such as air or shipping ports. The development and application of novel materials for powdering has recently received particular attention [9], [10]. In comparison to traditional powders, a range of reduced-size powder particles are now available for fingermark development purposes. These offer many potential advantages, not least that reduced particle sizes could offer enhanced resolution and allow better discrimination of finer characteristic detail within the friction ridges at the micro- or nano-metre scales. Furthermore, the chemical nature of smaller particles can also be tailored to enhance practical application. For example, powders grafted with fluorophores [9] or near infra-red absorbing materials [11] have recently improved fingermark detection on low-contrast surfaces. In some cases, application of selective powder materials has revealed additional information regarding the depositor (e.g., the presence of drugs or metabolites) [12], [13].

The lack of translational research, and owing to the poor prosecution rate of those involved in the illegal wildlife trade with its link to organized crime, has led the Metropolitan Police Service in London to conduct an investigation into efficient methods for the recovery of identifiable friction ridge detail from ivory obtained from a number of different species. The aim of this work was to perform an independent assessment of the potential benefits offered by reduced particle size powders for the retrieval of ridge detail from elephant ivory in comparison to a conventional powder. The objectives were:

(a)
to compare the physicochemical properties, sensitivity and practicality of two reduced-size powders (≤ 40 μm average particle diameter) relative to a conventional powder material (> 100 μm average particle diameter) for potential deployment in the field;
(b)
to perform an assessment of enhanced ridge detail quality with respect to location on a tusk and the age of deposits; and
(c)
to compare reduced-scale powders with fluorescent/non-fluorescent cyanoacrylate and to evaluate any benefits of sequential treatment.

This work, for the first time, presents the most comprehensive assessment of a new method for the recovery of usable ridge detail from elephant ivory tusks and performed within an accredited forensic case-work laboratory environment. Furthermore, the value of such an approach also lies in providing a potentially viable, field deployable tool to combat illegal elephant poaching at source.

Section snippets

Materials

The development powders used in this study were SupraNano Black Magnetic and SupraNano Black Powder (ARRO SupraNano Ltd., Newcastle upon Tyne, UK) and also Jet Black magnetic powder (WA Products Ltd., Essex, UK). Standard squirrel brushes (Tetra Scene of Crime Ltd., Essex, UK) or metal magnetic brushes/wands (Tetra Scene of Crime Ltd.) were used for powder application. Adhesive tape (Warrender Products, Gwent, UK) was used for the lifting of all developed areas of ridge detail. Exposed

Comparison of powder materials for fresh latent ridge detail on glass, photographic paper and ivory

Both the SupraNano Black Magnetic and Jet Black magnetic powder types were more easily controlled and applied than the SupraNano Black Powder. The black pigment of both reduced-scale powders was darker than that of Jet Black magnetic, which was grey in colour. Both reduced-scale powders were found to interact well with synthetic fingermark deposits on glass with good contrast, but adhered more strongly in general to the synthetic sebaceous pad-generated deposits. All powders bound to natural

Conclusion

This research has enabled a better understanding of the potential for improved detection of usable latent ridge detail on elephant ivory using reduced-scale powders. All powders developed more ridge detail and with better quality ridge detail in comparison to cyanoacrylate. All development techniques were less effective with ageing of deposits on ivory. However, reduced-scale powder could enhance latent ridge detail up to 28 days after deposition, but the best results were achieved within one

Acknowledgements

Many thanks to the staff of Metropolitan Police Service Fingerprint Bureau at New Scotland Yard, the MPS Specialist Forensic Services Imaging Team and Fingerprint Laboratory. Thanks are also extended to Gema Vizcay-Barrena at the Centre for Ultra-structural Imaging at King's College London and to Jim Davy UCL Earth Sciences for assistance with scanning electron microscopy and to Colchester Zoo for their assistance with the elephant and tusk physiology.

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Wildlife forensics is defined as providing forensic evidence to support legal investigations involving wildlife crime, such as the trafficking and poaching of animals and/ or their goods. While wildlife forensics is an underexplored field of science, the ramifications of poaching can be catastrophic. The consequences of wildlife crime include disease spread, species and habitat loss, human injury, and cultural loss. Efforts to use forensic science to combat poaching are currently limited to DNA-based techniques. However, fingermark analysis for the identification of perpetrators of wildlife crimes has not been explored to the same extent, despite being a cost-effective, simple-to-use forensic method that is easy to deploy in-field. This review covers literature that has explored fingermark examination techniques used on wildlife-related samples, such as pangolin scales, ivory-based substances, bone, and eggs, as well as feathers and skins, among more obscure trafficked items. Useful preliminary work has been conducted in this subject area, demonstrating that commonly used fingermark analysis techniques can be applied to wildlife-based items. However, many of these studies suffer from limitations in terms of experimental design. More work should be done on creating studies with larger sample sizes and novel approaches should be validated under environmental conditions that mimic real crime scenes. Further research into determining the forensic fingermark analysis techniques that perform the most efficiently in the environmental conditions of the countries where they are needed would therefore benefit legal investigations and help to reduce instances of poaching.
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Fingermark detection research aims to improve the quantity and quality of fingermarks detected through the development of novel techniques. Subsequently, there is a need to evaluate these methods to determine the quality of the developed mark. Since the 1980’s there has been a significant number of publications, which utilise a variety of different quality assessment methods. The introduction of common practice methods from the International Fingerprint Research Group (IFRG) aimed to implement a more standardised approach. Although these schemes are recommended as common practice, they are only guidelines. Consequentially, there is currently no universally accepted method to evaluate the enhancement techniques implemented in research. Therefore, this study aimed to collate and analyse the published protocols being used within fingermark detection research in order to better understand their application and how research is currently analysing and interpreting fingermark quality. This study comprised of manual and automatic searches of over 2000 published papers within the fingermark detection area. After thorough analysis of the articles, 396 published papers were found to have used a scale within the years spanning 1998–2022. The number of publications that report the use of a scale to assess quality for fingermark detection research has considerably increased over the last decade. However, whilst the number of publications utilising scales has increased, it is not proportional to the number of papers using the IFRG scales. The choice of scale is often institution specific and even more specific to their location. There are also numerous different adaptations of the IFRG recommended scales, as well as novel scales, which do not associate with the IFRG recommended versions being introduced the more research continues to grow. One such reason for this is investigated here, as different quality parameters are utilised within each individual scale. There is underrepresentation of these quality parameters within some of the IFRG scales, in particular the Centre for Applied Science and Technology (CAST) scale. This correlates to the considerable number of tailored approaches as authors are forced to add these parameters within the descriptions. Until there is an introduction of clear guidelines surrounding all areas of fingermark quality, from definition to parameters chosen within phases, the research area will continue to face such issues. This article recommends areas of potential study, whilst also recommending procedures that may be employed to alleviate some of the issues seen with fingermark quality evaluation.
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The retrieval of fingerprint friction ridge detail from elephant ivory using reduced-scale magnetic and non-magnetic powdering materials

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials

Comparison of powder materials for fresh latent ridge detail on glass, photographic paper and ivory

Conclusion

Acknowledgements

Forensic Sci. Int.

Sci. Justice

Forensic Sci. Int.

Forensic Sci. Int.

Opt. Mater.

Forensic Sci. Int.

Sci. Justice

Forensic Sci. Int.

J. Chromatogr. B

Forensic Sci. Int.

Endeavour

J. Hazard. Mater.

J. Aerosol Sci.

Elephant conservation, illegal killing and ivory trade