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1.
Forensic Sci Int ; 327: 110988, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34521020

RESUMO

The development of fingermarks on reflective surfaces is often a challenge regarding the photography of images with overlapping lines, low contrast and reflections, especially considering that many forensic laboratories are supplied only with basic instrumentation for fingerprint analysis. The present study overviews these difficulties and proposes a combination of chemical and optical procedures, using low-cost products and equipment, to develop fingermarks on silver mirror surfaces. The chemical treatment promotes the delimitation of the substrate, transforming the reflective surface into a transparent surface. The results were statistically analyzed, indicating quality improvement of natural fingermarks pictures taken with standard digital camera on transparent surface. There was good observation of details and minutiae, even for samples recovered several days or weeks after deposition. The suggested method substantially modifies the composition of the substrate without any contact with the fingermark, preserving its characteristics and properties. Like other nondestructive methodologies, this approach could be prioritized over methods that directly change the evidence itself and allows for the photography of the fingermark in unaltered condition. Lastly, it does not impact on the efficiency of subsequent exams.


Assuntos
Dermatoglifia , Ciências Forenses/métodos , Fotografação , Prata/química , Feminino , Humanos , Masculino , Propriedades de Superfície
2.
Soud Lek ; 66(3): 39-42, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34551558

RESUMO

ntomology, as a vast scientific discipline of zoology, deals with the study of insects, which are an integral part of the ecosystem of our planet and are closely linked to the activity and life cycle of all organisms, including humans. As a result of this natural connection, insects often become a direct “living witness” of a crime and thus an invaluable part of the evidence in a comprehensive forensic investigation, which in such cases necessarily includes a specialized field of science - forensic entomology. The goals of forensic entomology include comprehensive analysis of entomological evidence material and the use of knowledge about insects and other invertebrates for the purpose of investigating and verifying evidence in civil and criminal law. In practice, forensic entomology falls into several categories, including the issue of food pests in industry or agriculture, human and animal parasitology (especially myiasis) and very often the field of criminology and forensic medicine, where the results are mainly applied to determine the length of post mortem interval (PMI), evidence of manipulation of the corpse, or other forensic facts that results from entomological analysis. The conclusions of the entomology study are in many cases an invaluable part of the amount of information that leads to the answer of key questions in complex forensic evidence, especially in the group of serious crimes.


Assuntos
Entomologia Forense , Animais , Ecossistema , Medicina Legal , Ciências Forenses , Humanos , Mudanças Depois da Morte
3.
J Forensic Leg Med ; 83: 102253, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34543893

RESUMO

BACKGROUND: Blast related deaths are often shrouded by diagnostic and medicolegal complexities requiring multidisciplinary expertise in order to gauge accurate identification of the victims and document scientific investigations comprehensively. In the advent of more sophisticated technology, anthropologic methods can now be applied into post mortem imaging interpretation. The traditional imaging roles of characterizing osseous fragmentation, detecting and localizing foreign bodies can be expanded to simulate and support physical anthropologic examination to assist in documentation for court proceedings. CASE PRESENTATION: An assemblage of unidentified, incomplete, highly fragmented skeletal remains were found scattered on a bare area of land in a forest. There was evidence of an explosion given the pattern of scattered evidentiary material of explosive and ballistic nature. Laboratory analysis of white powder found within the explosive material confirmed the presence of high impact C4-explosive trace containing cyclotrimethylene trinitramin [Royal Demolition Explosive (RDX)] & pentaerythritol tetranitrate (PETN). It took meticulous multidisciplinary efforts to confirm the identity of the victim that was marred by the severe fragmentation and skeletalization of the remains. The initial radiologic interpretation focused more on identification of foreign bodies and supporting documentation of fragmentation. With the current availability of post computed tomography (PMCT) in our center, we reexamined the value and potential of PMXR and PMCT as an adjunctive tool for biological profiling. CONCLUSION: This was the first case of C4-blast related death reported in Malaysia. The multidisciplinary approach in efforts to identify the victim may serve as a guide in managing, coordinating and maximizing the expertise of different forensic specialists, with emphasis on anthropologic and radiologic collaboration.


Assuntos
Determinação da Idade pelo Esqueleto , Traumatismos por Explosões , Restos Mortais/lesões , Osso e Ossos/lesões , Antropologia Forense/métodos , Ciências Forenses/métodos , Determinação do Sexo pelo Esqueleto , Adulto , Restos Mortais/anatomia & histologia , Restos Mortais/diagnóstico por imagem , Osso e Ossos/anatomia & histologia , Osso e Ossos/diagnóstico por imagem , Substâncias Explosivas/análise , Feminino , Humanos , Malásia , Radiografia , Tomografia Computadorizada por Raios X
4.
Forensic Sci Int ; 327: 110981, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34482285

RESUMO

Multi-metal deposition (MMD) is a versatile fingermarks detection technique adapted from the colloidal gold biolabeling. However, the tedious procedures of MMD makes it receive little attention compared with other methods. The aim of this study is to evaluate the efficacy of MMD technique on several common fabrics, which is considered notoriously challenging for latent fingermark detection. Four different MMD formulations were examined to process fingermarks deposited on nylon taffeta, polyester taffeta, polyester pongee and cotton sateen to determine the most suitable one and the influence of aging and water immersion were also determined through subsequent experiments. It was found that MMD I outperformed other three formulations and obtained excellent results on nylon taffeta, polyester taffeta and satin ribbon, with polyester taffeta and satin ribbon providing more than 30% of identifiable marks even for fingermarks aged over 28 days. Cotton sateen and oxford cloth failed to produce ridge details but evidence of "touch" were successfully visualized, which may contribute to further DNA extraction. Water immersion did have some observable influence on the quality of detected marks as part of the MMD reactant within fingermarks lost during immersion, but the result from nylon taffeta and satin ribbon is still satisfying with the percentage of marks scored 3 and 4 reached 30%. The result of this study confirmed the capability of MMD I in treated with fingermarks on several kinds of fabrics, and shows potential to promote this non-instrumentation dependent technique.


Assuntos
Dermatoglifia , Ciências Forenses/métodos , Manufaturas , Feminino , Coloide de Ouro/química , Humanos , Masculino , Nanopartículas Metálicas/química , Nylons , Poliésteres , Propriedades de Superfície , Têxteis
5.
Emerg Top Life Sci ; 5(3): 359-365, 2021 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-34369572

RESUMO

Scientists are increasingly becoming better prepared to communicate science in a variety of different settings, yet significantly less attention has been paid to communicating science in the courtroom, a setting which carries major societal impact. This article explores key issues surrounding science communication in the courtroom. We outline a conceptual system for communication training that includes ideas about fostering greater collaboration across different stakeholder groups, and training expert witnesses to communicate scientific evidence in ways that are accessible and accurate. Critical to this concept is supporting communication that upholds the integrity of the science, while also maintaining expectations for interactions in the courtroom.


Assuntos
Comunicação , Ciências Forenses
6.
Talanta ; 234: 122608, 2021 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-34364421

RESUMO

This paper presents a structured workflow for glass fragment analysis based on a combination of Elemental Analysis using PIXE and Machine Learning tools, with the ultimate goal of standardizing and helping forensic efforts. The proposed workflow was implemented on glass fragments received from the Israeli DIFS (Israeli Police Force's Division of Identification and Forensic Sciences) that were collected from various vehicles, including glass fragments from different manufacturers and years of production. We demonstrate that this workflow can produce models with high (>80%) accuracy in identifying glass fragment's origins and provide a test-case demonstrating how the model can be applied in real-life forensic events. We provide a standard, reproducible methodology that can be used in many forensic domains beyond glass fragments, for example, Gun Shot Residue, flammable liquids, illegal substances, and more.


Assuntos
Vidro , Aprendizado de Máquina , Ciências Forenses , Fluxo de Trabalho
7.
Fa Yi Xue Za Zhi ; 37(3): 293-294, 2021 Jun.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-34379896

RESUMO

Abstract: Abstract.


Assuntos
Entomologia Forense , China , Entomologia , Medicina Legal , Ciências Forenses , Humanos
8.
Fa Yi Xue Za Zhi ; 37(3): 295-294, 2021 Jun.
Artigo em Inglês, Chinês | MEDLINE | ID: mdl-34379897

RESUMO

Abstract: Entomological evidence provides entry points and clues for cases detection, in terms of estimation of the postmortem interval (PMI), and place and cause of death. In recent years, the feasibility of entomological evidence in practice has been proved by theories and cases. It especially plays an important role in the investigation of cases with unnatural death, no monitoring, and highly corrupt cadaver. However, there are still some key issues to be further studied and standardized before the application of entomological evidence to forensic practice, to improve the effect of entomological evidence in forensic investigation and trial. This paper retrospectively reviews key studies of the application of entomological evidence in forensic science, mainly including discussion of forensic entomology inspection standard, identification studies of sarcosaprophagous insect species, collection of sarcosaprophagous insect growth and succession data under different environments and forensic entomotoxicology. With the rapid development of information technology and biotechnology, applying artificial intelligence and whole genome sequencing technology in forensic entomology has become a new research direction, which can improve the application value and range of entomological evidence in forensic science.


Assuntos
Dípteros , Mudanças Depois da Morte , Animais , Inteligência Artificial , Entomologia , Ciências Forenses , Estudos Retrospectivos
9.
J Forensic Sci ; 66(6): 2208-2217, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34342895

RESUMO

The issue of distinguishing between the same-source and different-source hypotheses based on various types of traces is a generic problem in forensic science. This problem is often tackled with Bayesian approaches, which are able to provide a likelihood ratio that quantifies the relative strengths of evidence supporting each of the two competing hypotheses. Here, we focus on distance-based approaches, whose robustness and specifically whose capacity to deal with high-dimensional evidence are very different, and need to be evaluated and optimized. A unified framework for direct methods based on estimating the likelihoods of the distance between traces under each of the two competing hypotheses, and indirect methods using logistic regression to discriminate between same-source and different-source distance distributions, is presented. Whilst direct methods are more flexible, indirect methods are more robust and quite natural in machine learning. Moreover, indirect methods also enable the use of a vectorial distance, thus preventing the severe information loss suffered by scalar distance approaches. Direct and indirect methods are compared in terms of sensitivity, specificity, and robustness, with and without dimensionality reduction, with and without feature selection, on the example of hand odor profiles, a novel and challenging type of evidence in the field of forensics. Empirical evaluations on a large panel of 534 subjects and their 1690 odor traces show the significant superiority of the indirect methods, especially without dimensionality reduction, be it with or without feature selection.


Assuntos
Ciências Forenses/métodos , Mãos , Odorantes , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Funções Verossimilhança , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise de Componente Principal , Adulto Jovem
10.
J Chromatogr A ; 1654: 462462, 2021 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-34411835

RESUMO

The identification of ILRs in fire investigations has attracted great attention for decades, and background at fire scenes caused complex interference on ILR identification by contributing characteristic compounds. Aiming at exploring the correlation between the interference extent to gasoline identification and chemical composition/structure, two polystyrene-butadiene rubbers (SBr) with typical styrene contents involving alkylbenzene in molecules were selected particularly. The free burning residues in the presence and absence of gasoline were collected and analyzed via gas chromatography-mass spectrometry. It is striking that SBr with typical styrene content caused the most remarkable interference to gasoline identification as far as reported since it is even impossible to be distinguished from gasoline through chromatography profiles. Additionally, the molecular structure together with the chemical composition influences the interference extent as well. To trace the source of the remarkable interference from SBr, polystyrene, polybutadiene, as well as one polystyrene-butadiene-styrene block copolymer, were picked particularly due to their specific chemical relations. The results of target compounds analysis on the corresponding combustion residues revealed that the remarkable interference of SBrs originated from the combination of 'styrene' and 'butadiene' by contributing different target compounds. The results provide further support for the proposal of the correlation of the interferents chemical compositions with the interference extent. Furthermore, this study provides important references for fire debris analysis by predicting the interference of different substrates on the basis of their chemical composition.


Assuntos
Butadienos , Incêndios , Ciências Forenses , Gasolina , Butadienos/química , Ciências Forenses/métodos , Cromatografia Gasosa-Espectrometria de Massas , Gasolina/análise , Poliestirenos/química
11.
Emerg Top Life Sci ; 5(3): 349-357, 2021 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-34402863

RESUMO

In recent decades the use of forensic science in investigations and therefore its subsequent presentation within the courts has increased exponentially, fuelled by an increase in scientific advances, development of databases and greater access to scientists and their expertise. This explosion in the use of forensic evidence has not been limited to one single scientific domain, as there are a broad range of scientific disciplines, encompassed by the general umbrella term' forensic science'. Many of these involve commonly applied methodologies and are accepted by the courts with limited scrutiny. Where tensions exist concerning the use of science in the courtroom is when novel or emerging sciences and scientific techniques are introduced. This may be particularly evident when the demands of the investigatory phase, where those working want to apply all possible tools at their disposal to gather as much evidence as possible and the needs of the courts, where the evidence must scientifically robust and admissible for it to be presented before a jury, come together. This paper examines the implications for the court for emerging or novel sciences and scientific techniques. In such cases, the potential rewards of implementing the scientific process and the information these may contribute to an investigation provides a temptation to investigators to push for their operational use, with the unintended consequence of posing an issue to the court when considering whether to admit the evidence into the judicial process.


Assuntos
Medicina Legal , Ciências Forenses , Bases de Dados Factuais , Motivação
12.
J Forensic Sci ; 66(6): 2424-2437, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34363402

RESUMO

One of the first challenges that crime scene examiners have is determining if a substance is blood before performing analysis. Conventional methods of detecting blood involve the use of chemicals and different wavelengths of light in tandem with digital photography. However, these methods are destructive or provide false positives. Visible wavelength hyperspectral imaging (HSI) is a noncontact blood detection method that has been proven to provide accurate and reliable results. A novel application of this technique has been used for the detection and positive identification of bloodstained footwear marks, of different dilutions ranging from undiluted to 1:50 with distilled water, and on a range of substrates, and colors. Comparisons between HSI and conventional digital photography were made using a grading scale and analyzed using Mann-Whitney U-tests. The HSI technique was able to detect a statistically significant greater amount of tread detail on white tiles, laminate, carpet, and blue tiles compared with the digital photography technique, which was only superior on black tiles. Critically, the HSI technique was also able to determine that the footwear marks were made in blood. These results show that HSI will be useful in forensic investigations, where it is known that the perpetrator has walked through the victim's blood and left a trail of footwear marks at the crime scene. Even if the perpetrator had time to clean up afterward resulting in diluted stains, HSI would still be able to detect bloodstained footwear marks with a greater amount of detail compared with digital photography.


Assuntos
Manchas de Sangue , Imageamento Hiperespectral , Processamento de Imagem Assistida por Computador , Fotografação , Sapatos , Ciências Forenses/métodos , Humanos
13.
Front Cell Infect Microbiol ; 11: 695191, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34458160

RESUMO

High-throughput DNA sequencing technologies have facilitated the in silico forensic analysis of human microbiome. Specific microbial species or communities obtained from the crime scene provide evidence of human contacts and their body fluids. The microbial community is influenced by geographic, ethnic, lifestyle, and environmental factors such as urbanization. An understanding of the effects of these external stressors on the human microbiome and determination of stable and changing elements are important in selecting appropriate targets for investigation. In this study, the Forensic Microbiome Database (FMD) (http://www.fmd.jcvi.org) containing the microbiome data of various locations in the human body in 35 countries was used. We focused on skin, saliva, vaginal fluid, and stool and found that the microbiome distribution differed according to the body part as well as the geographic location. In the case of skin samples, Staphylococcus species were higher than Corynebacterium species among Asians compared with Americans. Holdemanella and Fusobacterium were specific in the saliva of Koreans and Japanese populations. Lactobacillus was found in the vaginal fluids of individuals in all countries, whereas Serratia and Enterobacter were endemic to Bolivia and Congo, respectively. This study is the first attempt to collate and describe the observed variation in microbiomes from the forensic microbiome database. As additional microbiome databases are reported by studies worldwide, the diversity of the applications may exceed and expand beyond the initial identification of the host.


Assuntos
Líquidos Corporais , Microbiota , Pele/microbiologia , Líquidos Corporais/microbiologia , Feminino , Ciências Forenses , Geografia , Humanos , RNA Ribossômico 16S/genética , Saliva
14.
Forensic Sci Int ; 327: 110947, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34454379

RESUMO

Face matching decisions in applied settings are typically carried out by trained face-matching professionals, known as facial reviewers and facial examiners. Recent research has demonstrated that short professional face-matching training courses are limited in improving face-matching accuracy, however, despite the existence of high-level training guidelines produced by the practitioner community the content, duration and delivery of training for facial reviewers and facial examiners are not widely understood in the academic research community. The current study aimed to address this gap in the scientific literature to better understand how different agencies train facial reviewers and facial examiners, using results collected from an international survey. The survey included questions on the duration, delivery and content of an agencies face-matching training. 24 face-matching agencies from five continents took part in the survey. A quantitative analysis of the survey results revealed that at the group level facial examiners received longer durations of training, covering more topics than reviewers and more frequently included one-to-one mentoring. However, the survey revealed large differences in the duration, delivery methods and content of training by individual agencies at both the facial review and facial examiner level and low inclusion of evidence-based training practices. These results should help researchers to better understand the diversity in training practices and durations of training between different agencies and may help explain the individual differences observed in the performance of face matching professionals in the literature.


Assuntos
Reconhecimento Facial , Ciências Forenses/educação , Humanos , Internacionalidade , Aplicação da Lei , Inquéritos e Questionários
15.
Forensic Sci Int ; 327: 110966, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34455401

RESUMO

Forensic hair analysis remains under the microscope. Although hair evidence can yield information pertinent to an investigation, past issues with associated expert testimony endure. The aim of this survey was to gain a better understanding of hair analysts by expanding on past findings by assessing methodology, terminology and bias, analysing demographic and workplace data and allowing participants to comment on current and future issues in hair analysis. An online survey was designed and disseminated to hair analysts worldwide and 176 analysts from 12 countries took part in the survey. Participants responded to questions regarding accreditation, the probative value of hair evidence, collection and packaging, contextual information, methodology, terminology and reporting results, conclusions and opinions. The probative value of hair evidence was supported and other than selection of mounting medium the survey identified a preference of collection methods, packaging materials, use of microscopy and notetaking. Terminology used when conducting hair analysis and reporting results varied and caution towards statistics was expressed while training and collaboration was encouraged. The survey data will be used in the development of validation studies in hair analysis for future dissemination.


Assuntos
Ciências Forenses , Análise do Cabelo , Humanos , Internacionalidade , Inquéritos e Questionários
16.
Med Leg J ; 89(3): 193-198, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34225527

RESUMO

Worldwide advances in computer techniques are not yet recognised in the practice of forensic medicine. A promising application is their use in making a three-dimensional reconstruction of the crime scene. This study analyses this technique in a homicide by firearm. Queries regarding the direction and number of shots, position of the victim inside the car when shot at and presence of the accused at the crime scene were answered by a scientific model. Similar reconstruction of the scene, nailing the accused in a heinous crime, has not previously been reported as a study or a case. The paper anticipates impetus to the growth of literature in criminology and forensic sciences. It will also expedite the delivery of justice based on scientific evidence in controversial causes of death.


Assuntos
Armas de Fogo , Homicídio , Computadores , Ciências Forenses , Humanos , Imageamento Tridimensional
17.
Forensic Sci Int ; 325: 110894, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34271326

RESUMO

This paper describes the involvement of our laboratory in a Western Australian 'cold-case' investigation that spanned 24 years. The investigation was widely considered to be the largest in Australian history. During the investigative phase, our laboratory was tasked with the collection of trace evidence of all types in connection with a sexual assault and two homicides that were suspected to be related. Textile fibres represented the vast majority of trace evidence recovered. A much greater quantity of fibres (>10,800) was collected than would be typical for a routine case, as fibres of any colour or type were potentially of investigative value. The investigation was unprecedented in its scale, and presented numerous challenges in terms of evidence recovery, analysis, interpretation, reporting, and provision of testimony. A textile fibre microspectrophotometric (MSP) database was developed specifically for the interpretation of data in connection with the investigation. The database currently contains over 25,000 normalised and first derivative spectra of casework, validation and reference textile fibres. A fibre comparison strategy was devised, involving the identification of preliminary fibre groups on the basis of corresponding/similar MSP spectra, and verification of these groups via brightfield and fluorescence comparison microscopy. A potential link to an automotive source was identified for one of the homicide victims during the investigative phase. After identification of a suspect, a total of 98 fibres recovered from victims and from a seized motor vehicle were found to correspond in properties to six different fibre types from known textile sources in connection with the suspect. A highly publicised criminal trial was held, and textile fibre evidence provided a major contribution to the trial findings, in which the accused was found guilty of two homicides.


Assuntos
Bases de Dados Factuais , Ciências Forenses/métodos , Têxteis , Austrália , Homicídio , Humanos , Microespectrofotometria , Espectroscopia de Infravermelho com Transformada de Fourier
18.
J Forensic Sci ; 66(6): 2413-2423, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34323303

RESUMO

The Natural Resources Conservation Service-Kellogg Soil Survey Laboratory has a large publicly available database of laboratory analyses of soil horizons collected from soil profiles largely from the United States. Among these soil properties are mineral grain counts from selected sand and silt fractions of soil horizons, performed by polarized light microscopy (PLM). These grain counts of over 20,000 fractions from 7534 sites provide a substantial reference that a forensic soil examiner could use to substantiate the rarity or commonness of a mineral species. The statement of the rarity or commonness of various minerals provide juries with additional context for the interpreting the results of a forensic soil comparison within the framework of a trial. The grain count data at specific locations can also be assessed to aid in soil provenance investigations, for cases where there are grain-counted sites in relevant locations. Two examples of application of these to data to soil evidence are included, one relating soil the rarity of a mineral (andalusite) to provide context in a soil comparison and one to aid in narrowing target regions in a soil provenance investigation.


Assuntos
Minerais/análise , Solo/química , Ciências Forenses/métodos , Sedimentos Geológicos/análise , Geologia/métodos
19.
J Forensic Sci ; 66(6): 2354-2361, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34328219

RESUMO

The prevalence of online child pornography is a major societal issue. The criminal justice system has struggled with assessing the risk of individuals involved in online sexual offenses against children, especially when it involves the possession of child pornography. Research suggests there are different categories of offenders involved in this type of behavior (e.g., Online Child Pornography Offenders, Dual Offenders, Contact Offenders), with each category having different motivations, contributing factors, and levels of risk to re-offend or escalate their criminal behavior to more serious offenses (i.e., collecting pictures to contact offending). Determining the risk that individuals involved in online sexual offenses against children pose to re-offend or escalate their criminal behavior has been problematic. Traditional sexual offender risk measures have lower predictive validity when dealing with online child pornography offenders. This article discusses the need for a formalized hybrid risk assessment model that combines the current online sex offenses against children risk measures with digital forensics artifact analysis. The evidence derived from digital forensics artifact analysis can supplement the predictive risk factors obtained from these risk assessment tools, thus increasing the reliability and validity of the risk assessment.


Assuntos
Artefatos , Literatura Erótica , Pedofilia , Medição de Risco , Criança , Criminosos , Ciências Forenses , Humanos , Internet , Delitos Sexuais
20.
Forensic Sci Int ; 325: 110898, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34247142

RESUMO

Freshwater diatoms offer valuable circumstantial forensic indicators, with a growing empirical research base aiming to identify and understand some of the spatial and temporal factors affecting their validity as trace evidence. Previous studies demonstrated that recipient surface characteristics, environmental variability, and individual species traits influence the initial transfer of freshwater diatoms to clothing. However, no previous research has sought to consider the impact of these and other variables on the persistence of transferred diatoms over investigative timescales. Therefore, this study aimed to identify and explore diatom retention dynamics on clothing following wear over time (hours to weeks). A series of experiments were designed to examine the impact of clothing material, seasonality, and time since wear (persistence interval) on the total number and species-richness of diatoms recovered and their relative retention (%) over time. Nine clothing swatches were immersed in a freshwater environment and then worn for one month in the spring. Subsamples were retrieved at regular intervals (e.g. 30 mins, 1 h, 8 h, 24 h) up to one month, diatoms were extracted using a H2O2 method, and examined microscopically. Three clothing materials were subject to the same experiment in the winter to generate a seasonal comparison. The results broadly identified three stages of diatom persistence on clothing - rapid initial loss, variable intermediate decay, and sustained long-term presence. Clothing material significantly impacted the number of diatoms recovered and retention dynamics over time, with complex interactions identified with seasonality. Although fewer diatoms were recovered in the winter, overall retention trends were consistent at the different times of year. The findings demonstrate that diatoms can be recovered from clothing, even weeks or months after an initial transfer, yielding a useful environmental trace indicator for forensic reconstructions over investigative timescales. The impact of clothing material and seasonality on persistence identified cotton, acrylic, and viscose clothing as the most reliable temporal repository of diatom trace evidence, with a more abundant forensic assemblage available for forensic comparisons in the spring.


Assuntos
Vestuário , Diatomáceas , Água Doce , Ciências Forenses , Humanos , Estações do Ano , Manejo de Espécimes
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