An investigation into the persistence of textile fibres on buried carcasses

Fibre persistence on submerged substrates: The effect of flow rate over extended submersion periods

Through both casework and research, fibres have been found to have the particularly useful ability to persist and remain exploitable after submersion. However, direct analysis of the persistence ability remains in early stages, and in particular, submersion times above a day have not been thoroughly studied. This study aims to both extend understanding of the impact of flow rate and submersion periods of up to 28 days. A blended polyester/cotton green fabric was abraded to increase transfer and then dragged over a black cotton substrate. Six replicates of these substrates were then submerged in artificial flow cells at various flow rates for 28 days. These were illuminated under UV light and photographed prior to submersion, at set times during submersion and after submersion. Another set of six replicates were imaged, submerged into a river and then recovered and re-imaged after 28 days. The population of fibres was then counted using these photographs, and a mix of one-way and two-way ANOVA tests were applied, in combination with Tukey's HSD, to detect significant differences across time and flow rate categories. Loss predominantly occurred on within the first 24 hours, in agreement with previous work. However, distinct from previous work there was a slow, approximately logarithmic loss over the balance of the submersion period. While significant differences were found between flow categories, there was no clear relationship between flow rate and persistence. The behaviour of the river samples was well-predicted by laboratory samples. 100 % fibre loss was never observed, with the maximum instead being 95.45 %. These results extend the understanding of fibre persistence on submerged substrates beyond the short submersion times in previous literature, and provide some deeper understanding of the impact of flow rate.

An investigation into the use of riverine mesocosms to analyse the effect of flow velocity and recipient textiles on forensic fibre persistence studies

Textile fibre evidence can provide important activity level information in criminal cases. To date, very few studies have investigated fibre persistence on fabrics exposed to aquatic conditions, even though items of evidence and victim's bodies can regularly be found in aquatic environments. This lack of research on whether fibres (and other trace evidence) persist on evidence submerged in water, has shown to impact practice as it is reported that crime scene examiners do not attempt to recover this evidence, due to the belief that it would not be present. The dynamic nature of aquatic environments mean that the studies are difficult to conduct in situ and variables, such as water flow rate are not possible to control and thought to be difficult to monitor. To address these challenges, artificial streams (also known as mesocosms) were employed in this study to investigate the persistence rate of polyester fibres on different fabric types (Woollen/nylon mix carpet, 100% polyester fleece, and 95% polyester/5% elastane sports vest) for a four week exposure time (1, 8, 24, 48, 120, 168, 264, 336, 504 and 672 hrs). The effect of water flow rate on the persistence of fibres was investigated by conducting the experiment with two flow velocities; 'high' (∼2.75 L/s) or 'low' (∼0.7 L/s). Significant differences between textile type were seen at 504 hrs under low flow conditions and 8, 24, 168 and 264 hrs under high flow conditions. When comparing flow velocities, a significant difference was seen at 1 hr exposure for the fleece textile only, indicating that the two flow rates used in this study do not significantly affect fibre persistence. Initial loss rates were highest for the first hour of submergence for the carpet, fleece and sports vest. Fibre persistence rates were highest on the carpet, followed by fleece and then sports vest. Persistence rates remained mostly constant after 24 hrs for all textiles but with redistribution of fibres between textiles being seen after this exposure time. The use of artificial flumes in this study provided a balance between realistic experimentation and a controlled study; key experimental variables could be continously and safely monitored. This study provides the first fibre persistence data in river type environments and proposes a new method for testing persistence in aquatic environments. This approach is not limited to fibres evidence and could be employed for other evidence such as glass, pollen, fingerprints and DNA.

The Veterinary Forensic Necropsy: A Review of Procedures and Protocols

Investigation of animal-related crime, and therefore submission of forensic cases to veterinary pathology facilities, is increasing, yet many veterinary pathologists are unfamiliar and often uncomfortable with involvement in the forensic necropsy. This article discusses various aspects of the forensic necropsy without specific attention to any particular species group or crime. General advice is given on procedures, documentation, and recording of the examination, and the article indicates how these features may differ from those used in investigation of natural disease. It also discusses evidence management, including recordkeeping, identification of evidence, labeling of photographs, and use of standard operating procedures and protocols. Various written and visual methods for documentation of the forensic necropsy are covered, and adjunctive topics such as sample collection, assessment, and description of wounds and taphonomy are included. Cause, mechanism, and manner of death are defined, and guidance to the use of these terms is given. The aim of this article is to offer guidance on procedural aspects of the forensic necropsy that will help those developing their forensic services, contribute to standardization of the provision of forensic veterinary pathology, and build the confidence of the "uncomfortable" forensic veterinary pathologist.