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 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.     

The population of coloured textile fibres in domestic washing machines.

A population survey was carried out to analyse examples of the coloured fibre population that may be expected to exist in both front- and top-loading domestic washing machines during Spring, in Sydney, Australia. White cotton T-shirts were washed both individually, and with a normal household wash load, then taped to recover extraneous fibres transferred during the wash cycle. Twelve thousand one hundred and seventy-eight fibres were classified according to length, colour and generic class. Cotton fibres were most prevalent (69.4%), followed by man-made fibres (24.2%). The most common colour/generic class combinations were black/grey cotton (27%), blue cotton (20%) and red cotton (15.6%). Other combinations generally represented under 2% of the total fibre population. Two thirds (65.9%) of the recovered fibres were under 2 mm in length, the proportion of fibres decreasing with increasing fibre length. Variations in machine type did not affect the distribution of fibres with respect to fibre type, colour or length.     

Influence of storage on larval length and age determination of the forensically important blow fly Lucilia sericata (Diptera: Calliphoridae)

One of the main tasks in forensic entomology is the determination of the minimum post-mortem interval (PMI_min) based on the age of the juvenile insects feeding and developing on the dead body. An important task is to store the evidence appropriately so that the evaluation and expert report can be used in court. However, existing recommendations can be contradictory or lacking scientific validation, e.g. by proposing various preservation liquids without knowing whether and to what extent the period of storage in such a liquid has an effect on the length of the preserved larvae. Storage time can be an issue since, due to technical and procedural circumstances, killed larvae may be stored for hours, days, weeks or even longer prior length measurement. A changed body length would have consequences for the entomological report, as the age of the larvae is usually derived from their length.This study investigates the effect of four differently concentrated ethanol solutions (70%, 80%, 90% and 96%) during a storage period of up to 196 days on the body length of stored larvae of the forensically important blow fly species L. sericata (Diptera: Calliphoridae). Larvae of different ages (24 h, 48 h and 72 h after hatching) were killed by immersion in hot, non-boiling water (≥80 °C) for at least 30 s. Their lengths were measured immediately. Subsequently samples were stored in ethanol of appropriate concentration at room temperature (approx. 22 °C). Further length measurements were made at 16 different storage intervals between 1 and 196 days.Many specimens showed a length decrease for most storage conditions and all larval ages. However, there was a tendency for 48 h- and 72 h-old larvae to increase in length after the first days of storage of up to 1.1 mm which may lead to an erroneous overestimation of the PMI_min using this kind of specimens. All changes in length within each cohort over total time were in the range of +7% to −9.1%. Significant differences in length changes within the first days of storage were found mainly in larvae stored in 70%- and 80%-ethanol, but larvae stored in 90%- and 96%-ethanol showed first significant differences on day 56 at the earliest.Our results lead to the recommendation that the measurements of fly larvae samples should be taken immediately after killing and before storage to avoid any effects. Ethanol ≥90% should be used for storage.     

Two-dimensional metric comparisons between dynamic bare footprints and insole foot impressions-forensic implications

Footwear may be found at crime scenes as physical evidence. Such footwear often has impression features of the wearer’s foot on the insole of the shoe. Scientific research and literature have established that footprints are distinct. This study compares two-dimensional measurements on bare footprints to foot impressions on insoles to determine if significant differences or similarities exist. Dynamic footprints were collected from 51 donors using the Identicator® Inkless Shoe Print Model LE 25P system. Seven foot length and width measurements were taken based on the Reel linear measurement method. Footprint measurements between bare footprints and foot impressions on the insoles were compared. Only two differences (p > 0.05) were observed between the various bare footprint and insole foot impression measurements on the right and left side for most of the measurements, CALC (p < 0.001) and A1 (p = 0.04). Bare footprint and insole A5 measurements on the left side were also significantly different (p = 0.015). The results of the study have implications in the forensic analysis of foot impression evidence on insoles in footwear in assisting with identifying the wearer of said footwear. Situations may arise in the forensic context when comparing the foot impression on the insole of footwear to a suspect’s bare footprint or a footprint from post-mortem remains. This study contributes to the scant literature available on the topic and to understanding the similarities and differences observed in the various linear measurements that may be utilized in the comparison process of footprint impressions on shoe insoles to bare footprints.     

Elemental analysis of white cotton fiber evidence using solution ICP-MS and laser ablation ICP-MS (LA-ICP-MS)

The purpose of this research is to investigate a method for the forensic elemental analysis of cotton fibers for the purpose of increasing the discrimination between otherwise similar cotton evidence using microwave digestion inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). A quadrupole ICP-MS and UV laser ablation (266 nm) instruments were used for the analysis. A cotton standard reference material (IAEA V-9) was used to validate the developed methods producing good accuracy with typically <10% bias and good precision (typically <5% RSD) for the element list: ²⁵Mg, ²⁷Al, ⁵⁵Mn, ⁵⁷Fe, ⁸⁸Sr and ¹³⁷Ba. It was found that the LA-ICP-MS method resulted in improved precision over the solution ICP-MS method. Twenty-four raw cotton samples and five white cotton T-shirts were analyzed with the developed methods. It was also found that all the raw cotton samples from different sources were distinguishable from each other, as were all the cotton T-shirts resulting in zero type I errors and zero type II errors for the pairwise comparisons. The laser ablation method was slightly faster than the solution-based analysis, requiring 3 h for the laser analysis of 10 samples vs. 3.5 h for the solution analysis, including sample preparation time. One additional advantage of the LA-ICP-MS method was the extremely low sample consumption (1.75 μg were consumed vs. 250 mg for the solution-based method) and the fact that the LA samples are amenable for reanalysis.     

Chemical Analysis in the Corpus Callosum Following Traumatic Axonal Injury using Fourier Transform Infrared Microspectroscopy: A Pilot Study

Evaluating traumatic axonal injury remains challenging in clinical and forensic sciences as its identification is difficult using routine diagnostic methods. This study used Fourier transform infrared microspectroscopy to detect TAI within the corpus callosum in an animal model. Protein conformational analysis revealed significantly increased β-sheet and β-turn contents paralleled by a decrease in α-helix content at 24 h postinjury, while the antiparallel β-sheet content was decreased at 12 h postinjury. Compared with the control group, the lipid/protein ratio was significantly reduced in all of the injured groups. At 24 h postinjury, there were increases in the olefinic=CH and CH₃ group of lipids accompanied by the decreased CH₂ group, but the results at 12 and 72 h were contrary to that at 24 h. Our study showed that FTIRM could differentiate injured from normal white matter at different time points following TBI via examination of these infrared spectral parameters.     

Transfer of fibres on the hands of living subjects and their persistence during hand washing

Textile fibres were transferred to the hands of ten living subjects and their persistence was determined after hand washing. Average number of fibres transferred was 300 ± 133 (female 288 ± 92, male 311 ± 163) per 100 cm² hand area in the 100 experiments. However the number of fibres transferred was not gender dependent but individual dependent. The hand texture of subjects was compared with the number of fibres transferred but the relationship was not observed. The number of fibres transferred varied significantly for the 10 repeated experiments performed under the same conditions for the same subject.The subjects were then asked to wash their hands with water. One test group washed their hands with standing water, and the other with running tap water. Afterwards, the number of fibres remaining on the test subjects' hands were investigated. Migration of the fibres on the surface of the observed hands did occur but total loss of transferred fibre after hand washing did not occur. The average number of fibres remaining per 100 cm² hand area was 14 ± 10 (range = 3–72) for hand washing with standing water, and 10 ± 12 (range = 0–79) for washing with running tap water. The results of this study show the possibility of finding fibres on the hands of a person involved in a criminal case even after hand washing before fibre collection.     

Blocks of colour IV: the evidential value of blue and red cotton fibres.

Samples of blue and red cotton fibres were examined using light and fluorescence microscopy as well as UV/VIS microspectrophotometry and fluorescence microspectroscopy. The degree of fluorescence and spectral variation was recorded. Particular attention was paid to the recurrence of certain spectral patterns. The importance of spectral information in the UV range is emphasized again. Colour plays a critical role in the comparison of cotton fibres in forensic sciences. Normally, fibres producing spectral patterns that are frequently seen will tend to have a lower evidential value in criminal cases as the choice of putative sources is theoretically greater and vice versa. Besides black cotton, blue and red cotton fibres are very frequent in fibre casework. The very high discriminating power using a combination of light microscopy, fluorescence microscopy and UV/VIS microspectrophotometry shows that even blue and red cotton fibres can provide excellent evidence when involved in fibre transfer cases.     

A quantitative assessment of the extent and distribution of textile fibre transfer to persons involved in physical assault

Knowledge of the number of fibres transferred during a particular activity is essential for the interpretation of findings in similar criminal cases. In this regard, violent contacts and physical assaults still present a challenge, due to a lack of robust published data. Hereby, we present the outcome of an empirical study where different assault activities were simulated by a Jiu Jitsu team and participants were asked to play either the role of an aggressive ‘assailant’ or a defensive ‘victim’, wearing cotton garments (i.e., Gi’s). Four different scenarios were simulated in replicates (n = 5), each of them involving different intensity levels (low and high) and duration times (30 and 60 s). Results showed that approximately 1,000 to 44,000 fibres were cross-transferred between the participants’ garments, with noticeable differences between the different scenarios. These values were significantly larger than those published in previous studies and, therefore, suggested the possibility of a current underestimation of the number of fibres transferred in physical assaults. Furthermore, statistical analysis by ANOVA indicated that the all the variables tested (i.e., intensity level, duration time, and participants role) had a significant effect on the number of transferred fibres (p < 0.001) and, consequently, that some knowledge of the case circumstances may be important to make more educated estimations. This is the first time that such a methodology has been applied for the quantitative assessment of fibre transfer between participants in assault activities. Data are expected to help practitioners with the interpretation of findings in real casework and lead to a more robust evidential assessment.     

Enzymatic extraction of dyes for differentiation of red cotton fibres by TLC coupled with VSC

The purpose of this work was to assess the usefulness of thin layer chromatography (TLC) for discriminating single cotton fibres dyed with red reactive dyes. An effective enzymatic extraction procedure with the use of cellulase for the red reactively-dyed cotton fibres was developed and used for the discrimination of fibres derived from 21 garments purchased commercially. Discrimination of the fibres relied on the separation of the extracted dyes by thin layer chromatography (TLC). Four eluents were used to develop the plates with the extracted dyes, and the obtained results were analysed using, among others, video spectral comparator (VSC). Observation of TLC plates in visible, ultraviolet and infrared light allowed unambiguous discrimination of 5 and probable discrimination of 6 of the 21 fibres tested. The remaining fibres were divided into several groups. Comparison of the acquired results with those obtained for the same examination material by standard non-destructive methods used in forensic fibres examinations (transmitted light microscopy, fluorescence microscopy, UV–Vis microspectrophotometry and Raman spectroscopy) has shown that efficiency in fibres differentiation is similar for all methods. TLC coupled with VSC was even found to be more effective in differentiation of red cotton fibres. The chemometric analysis was helpful to discriminate dyed cotton fibres, characterized by very similar colour.     

A textile fibre survey as an aid to the interpretation of fibre evidence in the Sydney region.

Frequency figures of the fibre population on textile cinema seats were measured in Sydney, Australia, in winter. Sixteen seats were analysed from a very popular cinema complex, with 3025 fibres classified according to colour, generic class and fluorescence properties (100 grey-black cotton fibres only). The recovered fibres were mostly natural fibres (84%) with cotton the most common generic type (70%). On the contrary, man made fibres were relatively rare (15%) with rayon constituting the majority of these (51%). The most common colour/generic class combinations were grey-black cotton (33%) and blue cotton (30%) accounting for 63% of the total population. All other frequencies were below 5%, most below 1% using only the two properties of colour and generic class. Fluorescence properties were found to be very discriminating as far as grey-black cotton fibres were concerned. These features are considered and discussed and in particular, to emphasise the significance of fibres as evidence of contact.     

The secondary transfer of fibres from head hair.

In this study, the effects of fibre type, hair style, time and fibre persistence on the secondary transfer of mask fibres to pillowcases via head hair were studied. Volunteers with a range of hair styles, and masks consisting of different fibre compositions were used in the study. Fibres from the masks were found to transfer from donor subjects to the pillowcases up to 14 nights after the mask had been worn. On average, the number of secondarily transferred fibres found decreased with time; however, this decrease appeared to be more 'linear' in nature, rather than an exponential decay. The greatest degree of secondary transfer occurred with cotton, then acrylic, then wool. In a primary transfer/persistence experiment with a 50% acrylic/50% wool mask, wool was found to persist in the hair more readily than acrylic. The results also showed that the greatest degree of secondary transfer occurred via short straight and long straight hair, with no clear pattern emerging between medium length hair (both straight and curly) and with long curly hair. The implications of these findings for the assessment and interpretation of casework are considered along with data obtained from related studies.     

Acute Benztropine Intoxication and Fatality

A woman was found unresponsive with an empty bottle of Cogentin^® prescribed to another. Admitted to an area hospital, her condition steadily declined until death 29 h after admission. Following toxicological screening on hospital (admission) whole blood, the only significant compound detected was benztropine. Benztropine was confirmed at 0.28 mg/L – the highest antemortem blood concentration recorded in a case of toxicity or fatality uniquely associated with benztropine. A second serum antemortem specimen showed a benztropine concentration of 0.19 mg/L. Despite over 24 h in the hospital, benztropine was also found in the postmortem specimens collected at autopsy. Peripheral blood, central blood, liver, and gastric concentrations were 0.47 mg/L, 0.36 mg/L, 9.6 mg/kg, and 44 mg, respectively. These results indicate that benztropine exhibited a potential difference between whole‐blood and serum (plasma) concentrations. Additionally, in consideration of literature data, benztropine was found indicative of a compound prone to at least some postmortem redistribution.     

Standardization of Histological Procedures for the Detection of Toxic Substances by Immunohistochemistry in Dipteran Larvae of Forensic Importance

Immunohistochemistry (IHC) technique is an alternative toxicological analysis to detect drugs in insects of forensic importance, but it requires thorough histological procedures. In this study, we tested different fixatives—phosphate‐buffered paraformaldehyde 4% (PP), Carnoy's fluid (CF), Kahle's solution (KS), ethanol in different concentrations, and ethanol associated to PP and CF, time of fixation and histological processes for dipteran larvae's tissue, aiming to develop a sample preparation protocol for IHC application. A suitable fixation was achieved using PP for 12 and 24 h, CF for 3 h, 70% ethanol for 19 days, and 70% ethanol/CF for 2 h/3 h. Postfixation using negative pressure, two immersions in xylene for 30 min each, and one in xylene plus paraffin for 45 min increased tissue preservation. An immunohistochemical test for cocaine detection was performed using monoclonal benzoylecgonine antibody from mouse, peroxidase‐conjugated anti‐mouse IgG and visualized by 3,3′‐diaminobenzidine method showed these histological procedures didn't compromise antigenicity.     

The population of coloured fibres in human head hair.

In 2002 a population study of textile fibres in human hair was carried out using 26 volunteers in Cambridgeshire, UK. Over 12,000 fibres were recovered from a variety of hair lengths using low adhesive tape and classified according to colour, generic type and fibre length. The results of the study showed that the most common fibre colours were black/grey (48%), blue (29.1%) and red (12.7%), the least common being green, orange/brown and yellow which each accounted for less than 5% of the total. Natural fibres (mainly cotton) were predominant (72.3%) and man-made fibres were considerably less frequent. When colour and generic type were classified together, the most common combinations were black and blue cottons. The least common were the man-made fibre/colour combinations with the most frequent of these accounting for less than 7% of the sample. Fibre loads carried by long hair were found to be significantly less than that carried by short hair. The results of this study are in accordance with previous fibre population studies using other types of recipient surfaces and are likely to be influenced by factors such as seasonal and geographical variation.     

Detection of dermcidin for sweat identification by real-time RT-PCR and ELISA

We evaluated the performance of real-time RT-PCR and ELISA assays for detection of dermcidin (DCD) in sweat and body-fluid stains. DCD, a small antibiotic peptide secreted into human sweat, was detected by real-time RT-PCR in 7-day-old stains containing as small as 10 μL of sweat, and the assay showed high specificity when testing 7-day-old stains containing 30 μL of other body-fluid. ELISA using anti-human dermcidin mouse monoclonal antibody detected DCD sweat diluted up to approximately 10,000-fold and could specifically detect DCD in 10 μL of body-fluid stains. The performance of the two assays was tested during winter on samples that simulated forensic case samples: an undershirt and a sock worn for 20 h, a handkerchief used to wipe the brow several times within 12 h, a cap and a cotton glove worn for 4 h, and a white robe worn at intervals for 2 years. The result showed that the former assay detected DCD in all sites of the undershirt examined (armpit, back, and breast), and the latter gave a relatively high OD value in the armpit among the three sites. For the socks, although the latter assay gave very high OD values in both the center and toe of the foot sole, the former could not detect DCD in both of them. These results indicate that highly damp conditions, such as inside a shoe, might promote the degradation of mRNA in samples such as socks. In the other case samples, sweat was adequately detected by both assays.This study is the first demonstration of the use of real-time RT-PCR to sensitively identify sweat among body-fluid stains, and it confirmed that dermcidin was an excellent marker for sweat identification. In addition, the usefulness of ELISA was also verified. Positive sweat identification using these assays is expected to assist forensic practice.     

Brain Fluid Content Related to Body Position and Postmortem Interval – An Animal Model

Adult male Sprague Dawley rats were euthanized and placed in a horizontal or vertical (head‐down) position at room temperature, after which brain fluid content was measured by a moisture analysis technique at variable time points. No significant difference in brain fluid content was observed between horizontal and vertical postmortem positions. A significant increase in brain fluid content was demonstrated 3, 6, and 24 h after death, with maximal fluid content observed at 24 h. Specifically, the brain fluid content of control animals was 77.79 ± 0.36%, increasing to 80.05 ± 0.22% at 24 h (p < 0.0001). This study has demonstrated no significant differences in brain fluid content related to postmortem position, suggesting that a head‐down position is not associated with increased brain fluid content or swelling. However, significant temporal increases in brain fluid content after death, most likely related to cerebral liquefaction, occur.     

Test of chlorine wipes for efficient removal of DNA from forensic genetics laboratories

Sodium hypochlorite is an efficient reagent for removal of unwanted DNA from laboratory surfaces. Here, we tested two different chlorine wipes and compared their performance to a 0.9–1.8% hypochlorite solution. WipeClean Chlorine Disinfection wipes contain > 0.1 g sodium hypochlorite/kg, whereas WetWipe Chlorine Desinfection wipes contain > 1000 ppm active chlorine. Clean surfaces were contaminated with 10 µL 0.5 ng/µL of massively parallel sequencing libraries. The DNA was dried and left for 45 min before any treatment. The surfaces were cleaned using either 1) a 0.9–1.8% hypochlorite solution and clean wipes, 2) a WipeClean wipe, 3) a WetWipe, or 4) the surface was not cleaned. All experiments were repeated three times. Subsequently, the surfaces were swabbed using cotton swabs. DNA was extracted from the swabs and the DNA concentrations were determined in quadruplicates by real-time PCR. This protocol was repeated after the soft plastic wrapping around the wipes were left open or closed for several weeks. The results showed that the WipeClean wipes efficiently removed DNA for up to four weeks after the box with the wipes were opened, whereas the WetWipe wipes dried faster and gradually lost their cleaning effect.     

5-(4-Nitrophenyl)-2,4-pentadien-1-al (NPPD) used as a tracer by nonscientists at a simulated crime scene

5-(4-Nitrophenyl)-2,4-pentadien-1-al (NPPD) was used as a tracer by nonscientists at a simulated crime scene. A card with both a plastic-coated smooth surface and a porous cellulose matrix paper surface was coated with a methanol solution containing 0.5mg/mL of NPPD. The card was touched with bare fingers and fingers covered by a cotton glove. A color-change protocol was then used to detect the presence of NPPD. The bare fingers or the fingers of gloves were swabbed with a cotton swab, or the parts of the glove that had touched the card were cut out. The swabs or the cloth pieces were dipped in methanol, a 0.1% methanol solution of naphthoresorcinol was added, and then concentrated hydrochloric acid was added. The observation of a red color at this point indicated a positive test. NPPD was easily observed in the experiments involving bare fingers, but no color change was observed from the swabbing of the cotton glove. However, when the cloth pieces cut from the fingers of the glove were subjected to the test, the red color was observed. In an attempt to enhance the sensitivity of the test, the volumes of the reagent solutions were reduced, but no improvement in sensitivity was obtained.