SCIJUS-00432; No of Pages 4 Science and Justice xxx (2014) xxx–xxx

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An investigation into the persistence of textile fibres on buried carcasses Roslyn DeBattista ⁎, Helen Tidy, Tim J.U. Thompson, Peter Robertson School of Science and Engineering, Teesside University, Middlesbrough, Cleveland TS1 3BA, United Kingdom

a r t i c l e

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Article history: Received 8 December 2013 Received in revised form 11 March 2014 Accepted 14 March 2014 Available online xxxx Keywords: Forensic science Fibre persistence Forensic archaeology Skin Taphonomy Burial

a b s t r a c t 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. © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

1. Introduction Textiles form an important part of our everyday life. Their high frequency of occurrence and the ease with which they are potentially shed upon contact form the primary reasons why they are so commonly encountered in forensic casework. For this reason fibres are a key trace evidence type as their presence at a crime scene, on a victim or on a suspect signifies contact which is potentially highly significant when presented in a courtroom. From the late twentieth century to the present, research has looked at the transfer and persistence of fibres in various medico-legal scenarios. This has been done to aid the forensic scientist in determining how fibres are transferred from one item to another and how long these fibres are subsequently retained in a given context. Minimal research however, has been conducted on the persistence of fibres on skin. Palmer and Burch [1] investigated the transfer and persistence of fibres on the skin of living individuals with results demonstrating that there was an initial rapid loss of fibres from the transferred location followed by an exponential decay. All fibres were found to be lost after 24 h (experimentation duration) although it was noted that shorter fibre lengths were more persistent. Cotton was found to be more persistent than polyester. Krauss and Hildebrand [2] looked at the persistence of fibres on the skin of carcasses left in an open-air environment. Their study concluded that the number of retained fibres was largely ⁎ Corresponding author at: Heritage Malta, Conservation Division, Diagnostic Science Laboratories, Ex-Royal Naval Hospital, Marina Street, Bighi, Kalkara KKR 1524, Malta.

dependent on weather conditions. Fibre loss increased drastically when wind and precipitation was present. However, there was never a complete loss of fibres throughout the duration of the experimentation phase (14 days). Palmer and Polwarth [3] also investigated fibre persistence on the skin of remains deposited in an open-air environment. Similar to the previous study, fibre loss was found to be dependent on weather conditions. In the absence of strong wind and precipitation, the loss of fibres was exponential, however, in stronger winds and heavier rainfall rate loss increased. The majority of the transferred fibres were lost within the first two days. Persistence of some fibres continued to be recorded until the conclusion of the experiment at day 12. It is a common worldwide practice for criminals to bury the remains of their victims in soil so as to conceal their crime. In such an environment it would be expected that the loss of any fibre evidence would be high but this has not been investigated. Thus the aims of this research were to determine the worth of pursuing fibre evidence after a 14 day burial period, and to determine the effect of a soil environment on fibres transferred to skin by direct contact between the donor garment and skin. 2. Materials and methods 2.1. Skin source Since the use of human remains gives rise to a number of ethical and legal issues, porcine skin was used as a human proxy. Studies such as the ones carried out by Meyer et al. [4], Lavker et al. [5], Lavker et al. [6], Ge

http://dx.doi.org/10.1016/j.scijus.2014.03.002 1355-0306/© 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Please cite this article as: R. DeBattista, et al., An investigation into the persistence of textile fibres on buried carcasses, Sci. Justice (2014), http:// dx.doi.org/10.1016/j.scijus.2014.03.002

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et al. [7], Barbero and Frasch [8] and Liu et al. [9] have determined that there is a close similarity between porcine and human skin. In fact, these studies concluded that skin morphology [4–7,9], immunohistochemistry [6] and the permeability of porcine skin [8] bear strong similarities to human skin. Furthermore, as highlighted by Janaway et al. [10] there are also similarities in terms of body mass, weight and fat-tomuscle ratio of the animals as a whole. Four fully grown porcine hind legs were used for this investigation having dimensions approximately 70 cm in length, 35 cm in width and 15 cm in height. 2.2. Fibre source Cotton and wool were the two fibre types chosen for this investigation. These were used since fibre population studies have shown these to be two of the most commonly occurring fibre types within an environment [11–23]. Cotton fibres were obtained from a George™ white pure cotton polo-shirt and white wool fibres were obtained from a wool lined EMU Australia® display boot. These fibres fluoresced under UV light which was essential in order to facilitate the visualisation of the fibres on-site. Two porcine legs were used for each fibre type. 2.3. Burial phase The grounds at the College of Policing formerly the National Policing Improvement Agency (NPIA) at Crook, north-east England were utilised. The burial sites were given clearance from the Department for Environment, Food and Rural Affairs (DEFRA). In order to assess repeatability in results, two separate burials were carried out over two periods, in June and August of 2011. In both investigations four burial deposits were dug one metre apart from each other. This was done so that all depositions would be in a similar soil environment. The soil had a pH of 8, was non-clay based and of a medium consistency. All depositions were covered in wire netting cages reinforced by metal bars. These cages were used to reduce the potential of larger animals gaining access to the porcine legs and removing them from the burial site. However, the wire netting used had a diameter of 2 cm which allowed for smaller animals and insects to interact with the carcasses as would occur in a real scenario. The dimensions of the cages were approximately 1 m in length, 50 cm in

width and 40 cm in depth. As a result, all four deposits were approximately 1 m in length, 30 cm in width and 30 cm in depth. 2.4. Seeding the fibres on skin All work was conducted in a black-out tent. This created a dark environment which made it easy to visualise and photographically document the initial number of transferred fluorescent fibres on the skin prior to burial. Full personal protective equipment (PPE) was also worn by the team in order to ensure that contamination was kept to a minimum. Initially the bottom of the cage was placed inside the deposit after which the porcine leg was rested in it (Fig. 1). Prior to seeding the leg with fibres, J-Lar® tape was used to remove any fibres already present on the skin. This was done systematically and after repeating the procedure twice, the leg was viewed under UV light to ascertain that all foreign fibres were removed. The fibre source was then rubbed vigorously over the skin surface using hand applied forceful pressure mimicking a rough contact between garment and skin. Photographic documentation using UV lighting was then carried out. Post-imaging, soil was placed on the leg and the hole was filled to three quarters of depth before the top part of the cage was placed over and secured, after which more soil was placed until the deposit was fully covered. In this way the carcass was completely inaccessible to large predators. However, as mentioned previously, there was still the possibility for smaller organisms to gain access to the porcine leg thus still allowing bioturbation to occur. Several studies have reported the movement of objects in the soil as a result of this phenomenon [24–32]. In a forensic context this activity is highly significant since it also causes the movement of any potential evidence found deposited on or in soil. 2.5. Excavation phase After the 14 day period, excavation of the depositions was initiated using a stratigraphic approach. As the first porcine leg was uncovered, it was noted that the soil had adhered to the porcine skin. This did not allow the proper identification of any fibres that had persisted on skin since fluorescence could not be seen through the layer of soil that had adhered to the skin. Consequently, the porcine legs had to be carefully brushed down prior to photographic documentation. This routine would also need to be carried out at crime scenes for fibre recovery.

Fig. 1. The arrangement of the cages prior (top) and post burial (bottom).

Please cite this article as: R. DeBattista, et al., An investigation into the persistence of textile fibres on buried carcasses, Sci. Justice (2014), http:// dx.doi.org/10.1016/j.scijus.2014.03.002

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The brushes used were previously flicked and taped (using J-Lar® tape) several times in order to remove any loose fibres and hair prior to brushing. 3. Results 3.1. Recovery of porcine legs After the 14 day period there was no evidence of large animal disturbance on any deposit, however, it was noted that close to one of the deposits (c.a. 30 cm away) faecal matter believed to pertain to a large animal was found. This continues to sustain the reasoning behind the use of cages. It was also noted that there did not seem to be a large number of flies circulating around the general area before any of the porcine legs were recovered. Once excavation commenced on the first grave, an influx of flies was noted. These were seen settling on the top of the particular grave that was being excavated at the time. Numbers increased drastically once the first two layers (spits of 10 cm) were removed from each grave. Some beetles were also noted on the topmost layers of the graves where most insect activity could be seen. During the recovery of the first two layers from each grave, no odour could be detected. However, once the third layer was uncovered a pungent odour was present. It was also noted that the soil in the third layer, which was nearest to the remains, appeared darker than the rest of the soil — likely a result of the presence of decompositional products. Once most of the soil was brushed off the porcine legs, it was evident that their skins were moist and certain parts had turned black, however, overall not a considerable amount of decomposition had occurred. Furthermore, when the bottom cage grids together with the porcine legs were removed from each grave, a black–grey deposit was left behind on the bottom of each grave surface. Maggot activity was also observed. 3.2. Fibre persistence on skin Table 1 displays the initial number of fibres transferred on the porcine legs prior to burial and the number of persisted fibres which were detected on the skin post excavation for the two investigations. Fibre persistence results are also displayed as a percentage. 4. Discussion The two investigations demonstrated that in a burial environment, both cotton and wool fibres are able to persist on a skin surface for a period of 14 days. It must be highlighted however, that persistence after 14 days was not investigated and therefore persistence beyond this period cannot be commented upon. These results are highly significant as they prove that fibres can persist even when the carcasses were brushed down to remove the excess soil that had adhered to the porcine skins. This suggests that when rough contact between a fibre source and skin occurs, there is a Table 1 The initial number of transferred cotton (C) and wool (W) fibres in comparison with the number of persisted fibres detected on the skin post excavation. Porcine Leg

Fibre Type

Investigation 1 1 2 3 4

C C W W

Investigation 2 1 2 3 4

C C W W

Transferred Fibres

Persisted Fibres

Percentage Persistence (%)

384 467 106 50

11 13 11 8

3 3 10 16

1461 1876 166 111

16 26 8 15

1 1 5 14

3

high probability that transferred fibres may adhere well on the skin and persist even when buried in a soil environment. This adherence may possibly be due to the presence of decompositional products acting like glue. The results indicate that the number of fibres which persisted on porcine skins was higher for Investigation 1. It is very difficult to determine with a level of certainty why this is so, however, it is suspected the soil was wetter in Investigation 2 and thus more force was used during brushing, inadvertently removing more fibres. This suggests that at crime scenes involving similar scenarios, it is advisable to approach this task with minute pressure during brushing in order to preserve as many persisted fibres on the skin as possible. From the initial count of fibres present on porcine skin in both investigations, wool fibres transferred less than cotton fibres. This can be stated since the same type of contact was used when both cotton and wool fibres were being transferred onto the porcine skin. In contrast, there is no large discrepancy in the number of cotton fibres which persisted on skin in comparison to wool fibres. However, it is essential to take into consideration that the initial number of cotton fibres which were transferred on the porcine skin in both investigations was considerably higher than the initial number of wool fibres. This therefore gave rise to a difference in the number of persisted fibres for the two fibre types. This is clearly evident in the percentage persistence results displayed in Table 1. Whilst it is difficult to determine the precise reason why this difference has occurred, one suggestion might be that this could have occurred because cotton fibres are smaller in size and more volatile thus making them more sensitive to brushing than the thicker and heavier wool fibres. However, irrespective of this, these percentages bring about two main observations, primarily that in both investigations the percentage of fibres which persisted was higher for wool and that the percentage of fibres which persisted was higher in Investigation 1 for both fibre types. The former observation is interesting since the majority of published research has shown that the persistence of wool was consistent with the other fibre types under investigation [33–35]. However, there are two opposing studies which contradict these findings. A study carried out by Palmer and Banks [36] found that wool persisted more readily in head hair. It is stated that this might be due to the hair-on-hair interactions that occur as a result of their rough scaled nature. In contrast, Palmer and Burch [1] concluded that in their study, cotton was more persistent than wool fibres. Even though no definite answer can be given as to why the percentage of persisted wool fibres was more than cotton, it can be stated with a level of certainty that it was not because of any possible hair-on-hair interactions which might have occurred. This is so since no hair was present on the areas of the porcine skin onto which the fibres were transferred. The study by Palmer and Polwarth [3], where the persistence of wool and acrylic fibres on porcine carcasses left in an open-air environment for a period of 12 days was investigated, showed that from an initial wool fibre count of 619 fibres, 5 wool fibres persisted. In addition, out of an initial 374 acrylic fibres transferred only 3 of them persisted. Therefore, the percentage of persisted fibres for both fibre types was 1%. This means that in accordance with the study reported in this article, a reduced number of fibres are expected to persist in both open-air and buried environments. Furthermore, as also indicated in the Palmer and Polwarth [3] study, these results imply that in a real scenario, such findings could possibly represent only remnants from an initial forcible primary contact which in turn is of greater forensic significance. However, it can be noted that from the percentage persistence values obtained for the two environments, it is evident that more fibres persisted in a buried environment. Furthermore, these results are in agreement with the ones obtained by Krauss and Hildebrand [2] and Palmer and Polwarth [3] since a total loss of fibres was never seen and fibre persistence was always noted. This contradicts Palmer and Burch [1] since no fibres persisted on the skin of living individuals after 24 h. It must be argued however, that

Please cite this article as: R. DeBattista, et al., An investigation into the persistence of textile fibres on buried carcasses, Sci. Justice (2014), http:// dx.doi.org/10.1016/j.scijus.2014.03.002

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even though this study also looked at fibre persistence on skin, the arms of living individuals were used as opposed to static carcasses. Also after the transfer of the fibres, subjects were instructed to carry out their daily duties including showering or bathing. This means that unlike the study undertaken, the fibres were not transferred on dead remains which were static throughout the duration of the investigation. However, it is believed that fibre persistence studies on the skin of living individuals do complement the ones relating to static remains, such as the study being reported here, since the former can provide estimates of time frames for contact which is highly important when evaluating results in a Bayesian framework. From this study a number of recommendations can be given for future studies. When faced with the problem of soil adhering to skin, instead of brushing the carcass two other alternatives might be to tape the remains or to wash down the residue with distilled water and collect it. The residue could then be examined for target fibres. In order to determine if seasonal changes impact the persistence of fibres, it is recommended that the experiment is repeated in spring, autumn and winter. Using different types of soil and fibres could also help in establishing if other trends are obtained. Moreover, to possibly further determine if fibre loss is due to excavation or if there is a definite rateof-loss during burial, further experiments can be carried out involving the exhumation of the remains over different time intervals. 5. Conclusion This study has shown that persistence of wool and cotton fibres occurs when these fibres have been transferred onto the skin by rough contact and subsequently the remains have been buried in a soil environment for 14 days. It has also been shown that these fibres have persisted on skin even after the latter has been brushed to remove any soil adhering to it. Since the repeated burials show that persistence on skin occurred and that there was no large margin of difference in the number of persisted fibres, the results obtained suggest consistency. Both investigations showed that wool was more persistent than cotton and that the number of fibres which persisted was much less than the initial number of transferred fibres. From this study it is also possible to state that no porcine leg experienced a total loss of fibres which is also very significant as this possibly suggests that persistence might occur for longer periods. Although further investigations should be carried out to develop this work, it does suggest that those excavating human remains should do so with a view to recovering fibre evidence and that the appropriate equipment and expertise to undertake this fibre examination at the scene should be considered during the creation of the forensic strategy. Acknowledgements Special thanks go to Ms. Deborah Campbell, Mr. Ian Parker, Dr. Claudia Garrido Varas, Ms. Joanne Pierre, Ms. Claire Whitamore, Mr. Matthew Grima, the College of Policing especially Ms. Abigail Lagden and Mr. Michael O'Brien for contributing in one way or another to this research project. The research work disclosed in this publication was partly funded by the Malta Government Scholarship Scheme and Teesside University. References [1] R. Palmer, H.J. Burch, The population, transfer and persistence of fibres on the skin of living subjects, Sci. Justice 49 (4) (2009) 259–264. [2] W. Krauss, U. Hildebrand, Fibre persistence on garments under open-air conditions, Proceedings of the 3rd Meeting of the European Fibres Group, Linkoping, 1995, pp. 32–35.

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Please cite this article as: R. DeBattista, et al., An investigation into the persistence of textile fibres on buried carcasses, Sci. Justice (2014), http:// dx.doi.org/10.1016/j.scijus.2014.03.002

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...
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