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.

Planning and developing a method for collecting ground truth data relating to footwear mark evidence.

Ground Truth Data is data that comes from a known source, where the truth about the data is known and not inferred (FSR, 2021). The Forensic Science Regulator requires forensic units (that carry out certain forensic processes) to undertake tests against ground truth data for the purposes of quality assurance/quality control processes such as accreditation. However, the data collected must form a meaningful dataset that will enable relevant tests to be performed that inform the end-user. This technical note discusses how a forensic unit in the UK planned and developed a method for collecting ground truth data for footwear mark evidence. It discusses the materials and variables that were considered when developing the method and the evidence-based, decision-making processes that enabled its creation. Recommendations and considerations are provided to assist other forensic units collect data relevant to their jurisdiction. Whilst the method is not prescriptive, if it is used as a guide, it may facilitate the development of a large and relevant national dataset.

Plastics derived from disposable greenhouse plastic films and irrigation pipes in agricultural soils: a case study from Turkey.

Plastics are ubiquitous. It has been used in human activities, from agriculture to packaging, infrastructure, and health. The wide range of usage makes plastics an omnipresent pollutant in the environment. This study investigated the abundance and type of plastics in agricultural soil in the Adana/Karatas region in Turkey, where disposable low-tunnel greenhouse plastic films and irrigation pipes were in use. For this purpose, 1 kg of soil samples from the top 5 cm (from the surface) was taken from 10 different sampling locations. An average of 16.5 ± 2.4 pcs/kg was found in the soil samples. The highest amount of plastics was seen at the Bahçe-4 location with 39.7 ± 12 pcs/kg and the lowest amount of plastics at the Karatas-1 location with 0.7 ± 0.3 pcs/kg. The average size of plastics was found to be 18.2 ± 1.3 mm. The average size of plastics originating from greenhouse cover was 18.9 ± 1.4 mm, and from disposable irrigation pipes was 12.5 ± 3.5 mm. It was determined that 41.9% of extracted plastics were microplastics, 36.3% were mesoplastics, 16.3% were macroplastics, and 5.6% were megaplastics. Results indicated that residual plastics decreased in the soil where used plastics were removed after usage. As a result, it is worth noting that a significant amount of plastics remain in soil due to plastics being used in agricultural areas.

The creation of an assessment tool for the analysis of two forms of heat damage in animal hair.

Animal cruelty cases can involve a variety of mistreatment to domestic animals. A common source of abuse is the use of heat sources, such as ovens, hot surfaces and microwaves. Analysis of damage to skin by a veterinarian is a key aspect of these investigations but additional information can be provided by observing the hair of the animal, including heat source type and exposure time. This study developed an objective grading system for the analysis of heat damage in hairs which can be used to quantify different damage characteristics including bubbling, discolouration, expansion of hair, fractures, changes to the medulla and scales and scale removal/melting. This grading scheme was applied to the investigation of dog (Canis familiaris) skin samples with full pelage and loose hairs exposed to microwaves and a heated environment in order to identify any distinguishing damage characteristics from the two different heated environments. Samples were exposed to a furnace for 1min at different temperature ranges (50-350°C with 50°C intervals) and also a microwave at maximum power for different time periods (15, 30, 45, 60, 120, 180, 240 and 300s). Hairs were extracted for examination using high powered light microscopy and scanning electron microscopy. Overall, it can be determined that the type of damage observed is influenced by the nature of heat applied and the context and substrate in which the hair is situated at the time of exposure. Using principal component analysis (PCA) it was concluded that as temperature increases in a furnace so does the severity of each of the damage characteristics observed. It can be noted that with furnace exposure, any one of the characteristics could be used to indicate the temperature to which it has been exposed. For furnace exposed samples there was no significant difference between loose or embedded hairs. PCA analysis determined that there are two independent forms of damage that occur when hairs are exposed to microwave radiation, these are: increased bubbling and discolouration in the root and increased bubbling and discolouration of the shaft and tip. Exposure time is correlated with both the root and shaft/tip observations. The results indicated some clear distinctions between heat source and exposure useful for the objective interpretation of such evidence. This standardised approach for the observation of heat damage characteristics in animal hair provides investigators with a tool to differentiate between methods of abuse, providing a greater understanding of the crime committed.

An international survey into the analysis and interpretation of microscopic hair evidence by forensic hair examiners.

Due to inadequacies in historical hair examinations, the use and perceived value of microscopic hair evidence has reduced. Many reports have heavily criticised the use of pattern-based evidence including hair evidence as being unreliable, with police forces focussing on more individualising evidence. Hair evidence has been utilised in casework for many years due to its ability to transfer easily between individuals and crime scenes. Hair evidence can provide important information in criminal investigations, and in certain circumstances, aid in the identification of an individual, along with providing information to aid in the reconstruction of a crime scene. It has become apparent in recent studies, such as the 2012 FBI review, that hair evidence has been inappropriately utilised in case work and this, along with a preference for more discriminating methods such as DNA profiling, has led to both a lack of confidence in and reduction of use of hair evidence. The need for more standardised and objective methods is required along with improved methods for interpreting hair evidence. Since these reports, there has been no study investigating how these have affected the perceptions of hair evidence by forensic hair examiners or that has investigated what methods are being utilised to create a robust, objective and reliable interpretation of this evidence. This study aimed to assess the current similarities and differences in microscopic hair examinations and perceptions of its evidential value between countries, with a focus on the analysis and interpretation methods used by case work examiners and researchers. This study will discuss the findings of a survey and interviews completed by hair examiners. Previous surveys have been conducted by Aitken & Robertson (1986) and Murphy (2013), however the current international status of microscopic hair examinations is unknown. This study gathered responses across 9 countries. From this, it was identified that the microscopic examination of hair evidence is still valued highly by those practicing it. The amount of cases that an examiner has worked on that involve the examination of microscopic hair evidence is correlated to the perceived evidential value of hair evidence and to the value of morphological characteristics of hair. There are inconsistencies between the approaches used in interpreting this type of evidence. Subsequently, this study has generated an international understanding of the current status of hair examinations which was not previously known from an operational perspective.

The effect of tape type, taping method and tape storage temperature on the retrieval rate of fibres from various surfaces: An example of data generation and analysis to facilitate trace evidence recovery validation and optimisation.

This paper aspires to assist those tasked with data generation and analysis for the purpose of the validation and/or optimisation of trace evidence recovery. It does so via a detailed report of the authors' approach to this problem in the context of target fibre retrieval using self-adhesive tapes. Textile fibres can provide valuable evidence at both source and activity levels. This ability stems from their near ubiquity in the man-made environment, their potential for high levels of discrimination (especially when found in combination) and their reproducible transfer and persistence behaviours. To realise this value for the criminal justice system, it is vital that police forces and forensic providers are collectively able to search for, recover and analyse fibres found at crime scenes and correctly evaluate their evidential value. ISO accreditation provides quality assurance for such activities. The work reported in this paper was part of a study to validate crime scene fibre retrieval processes for the purposes of ISO17020 accreditation. However, it is hoped that it will be of assistance to those wishing to validate and/or optimise forensic fibre recovery whether at the crime scene or in the laboratory. Further, the methods described may be of value to those who need to validate and/or optimise the recovery of other types of trace evidence. This paper outlines a series of experiments that investigated the effect of four factors on the rate at which target fibres could be recovered from surfaces by tape lifting. The factors were tape type (with two levels, namely: J-LAR and Crystal Tabs), tape storage temperature (three levels: -5 °C, room temperature [19 ±â€¯1 °C] and 35 °C), taping method (two levels: zonal and one-to-one) and surface (12 levels: each being a surface type commonly encountered at crime scenes). This resulted in 144 unique experimental conditions. For each of these, five repeat fibre recovery rate determinations were carried out, generating 720 data points. All surfaces were clean and dry prior to target fibres being transferred and recovered. In all cases, the tapes were applied to the surfaces at 19 ±â€¯1 °C. These experiments showed that the surfaces can be divided into three stable clusters based on the median and interquartile range of the fibre retrieval rate achieved from each of them. Also, they showed that, in terms of the proportion of the target fibres retrieved, typically and setting aside interaction effects: However, notably, a good degree of between-condition overlap was also apparent in the data. To understand this, a four-way factorial ANOVA model was built which revealed significant and substantive effects for all four main effects and for 10 of the 11 interactions. Importantly, the four-way interaction term was amongst those found to be significant. The interplay between the effects of the four factors was analysed by means of simple effects tests and pairwise contrasts. Tables and interactive parallel coordinate plots have been created. Using these it can easily be seen which of any given pair of levels of each of the four factors resulted in the higher fibre retrieval rate under any one of the unique conditions of the study, and the effect size and statistical significance of this observation. Qualitative evaluations of the effect of tape storage temperatures on tape pliability and its propensity to tear in use were also made.

Quantification is more than counting: Actions required to accurately quantify and report isolated marine microplastics.

Research on marine microplastics continues to increase in popularity, with a large number of studies being published every year. However, with this plethora of research comes the need for a standardised approach to quantification and analysis procedures in order to produce comparative assessments. Using data collected from neuston nets in 2016, parameters for quantifying microplastics were compared. Surface area was the most accurate parameter to describe plastic size and should be used to describe plastic quantity (per km2 or m3), alongside abundance. Of the two most commonly used methods for calculating plastic concentration (flowmeter and ship's log), ship's log provided consistently smaller abundances, with the exception of one sample, calling for a standardisation in the techniques and measurements used to quantify floating microplastics.

Deep-sea anthropogenic macrodebris harbours rich and diverse communities of bacteria and archaea.

The deep sea is the largest biome on earth, and microbes dominate in biomass and abundance. Anthropogenic litter is now almost ubiquitous in this biome, and its deposition creates new habitats and environments, including for microbial assemblages. With the ever increasing accumulation of this debris, it is timely to identify and describe the bacterial and archaeal communities that are able to form biofilms on macrodebris in the deep sea. Using 16S rRNA gene high throughput sequencing, we show for the first time the composition of bacteria and archaea on macrodebris collected from the deep sea. Our data suggest differences in the microbial assemblage composition across litter of different materials including metal, rubber, glass, fabric and plastic. These results imply that anthropogenic macrodebris provide diverse habitats for bacterial and archaeal biofilms and each may harbour distinct microbial communities.

The design and implementation of a proficiency test for assessors of fingermark quality, to facilitate collaborative practise in fingermark research.

Significant numbers of institutions are carrying out fingermark based research, yet there appears to be little inter-institution consistency in the approaches used to assess the quality of the samples produced. Inter-institution consistency in quality assessment would lead to inevitable benefits in collaborating research projects, given that data from multiple projects may be combined, or compared. In order for such quality assessment schemes to be effectively used across multiple institutions, proficiency in using such approaches should be identified to ensure parity. Intra-institution controls on fingermark quality assessment are likely to help manage variations between researchers from the same institution and/or project(s). Proficiency testing (PT) is a popular means of comparing and monitoring the competency of individuals, whilst also assessing the validity of data and conclusions. This project aimed to develop a proficiency testing scheme for the assessment of fingermark quality for researchers. A grading system was developed to assess the quality of fingermarks generated within research projects. A large collection of test fingermark samples was created controlling variables such as force, fingermark composition and surface type. An 'inter-laboratory testing scheme' design was used for the proficiency test and established fingermark researchers participated in the project to produce known values for 6 chosen test samples for round one of the testing scheme, described in this paper. Second year BSc (Hons) Forensic Science and Forensic Investigation student participants from the host institution completed the proficiency test as part of a fingermark practical. Results indicated that student participants involved in this project were not able to demonstrate a satisfactory level of proficiency of fingermark quality assessment using this grading system, which was attributed to their relative experience in assessing the quality of fingermarks compared to 'experts' in fingermark analysis. Results have highlighted considerations for future grading systems, and additional training requirements of users.

Using a forensic science approach to minimize environmental contamination and to identify microfibres in marine sediments.

There is growing evidence of extensive pollution of the environment by microplastic, with microfibres representing a large proportion of the microplastics seen in marine sediments. Since microfibres are ubiquitous in the environment, present in the laboratory air and water, evaluating microplastic pollution is difficult. Incidental contamination is highly likely unless strict control measures are employed. Here we describe methods developed to minimize the amount of incidental post-sampling contamination when quantifying marine microfibre pollution. We show that our protocol, adapted from the field of forensic fibre examination, reduces fibre abundance by 90% and enables the quick screening of fibre populations. These methods therefore allow an accurate estimate of microplastics polluting marine sediments. In a case study from a series of samples collected on a research vessel, we use these methods to highlight the prevalence of microfibres as marine microplastics.