Identifying the scene of a crime through pollen analysis

The forensic analysis of pollen involves the comparison of crime scene and reference pollen samples. Successful matches are frequently used to solve time- or location-related crimes. Despite its prospects in criminal investigation, forensic palynology is still underused in casework due to inherent shortcomings such as its limited evidential weighting, scarcity of skilled palynologists dedicated to forensic casework and the laborious nature of analytical procedures. To address these challenges, the current state-of-the-art in forensic palynology is transiting from the traditional light microscopic methods that dominated the early days of palynology to more contemporary approaches like Raman spectroscopy, stable isotope analysis and DNA metabarcoding. The major challenges of these methods, however, include a lack of optimisation to forensic expectations and the unavailability of robust databases to permit accurate data interpretation, and quests to resolve these problems constitute the theme of current research. While reiterating the usefulness of pollen analysis in criminal investigation, this report recommends orthogonal testing as a way of improving the evidential weighting of forensic palynology.     

法医现场勘查学初析

法医现场勘查是公安法医检案的一个组成部分,与痕迹现场勘查各有侧重。本文通过室内、野外、运动空间三类现场初步分析了法医现场勘查的要点。     

Odor exposure and recall of a virtual reality crime scene: A preliminary study

Environmental context reinstatement has a particular value for recall of information in forensic interviews. Since odors are valuable memory cues and can act as memory triggers, in our preliminary study we explored whether odor exposure can help people recall details of a crime scene. The study comprised 58 women and 15 men aged 22–35 who immersed in a carefully controlled environment closely resembling an actual crime setting, i.e., a virtual reality crime. Participants were exposed to an odor at encoding, recall, both or neither of these instances, yielding a total of 4 experimental groups that further completed a memory recall task. The crime scene content recall was tested in a free recall and a forced-response test immediately after seeing the crime scene and one month later. We found no significant effects of odor exposure on the free or the cued recall of the crime scene. The memory scores correlated neither with the self-assessed olfactory/visual sensitivity of the subjects, nor with the perceived odor pleasantness. These preliminary findings suggest that introduction of a vanilla odor while encoding and recalling a crime scene does not aid witness recall accuracy.     

Virtual reality for teaching and learning in crime scene investigation

Simulated crime scene investigation is an essential component of forensic science education, but its implementation is costly and poses challenges to accessibility; offering personal investigations in higher education scenarios is often impossible. Virtual reality (VR) is an emerging technology which offers exciting prospects for teaching and learning, especially for imparting practical skills. We document here a multidisciplinary experimental study in which a bespoke VR crime scene app was designed and implemented, after which it was tested by both undergraduate student and staff/postgraduate student cohorts. Through both qualitative and quantitative analyses, we demonstrate that VR applications support learning of practical crime scene processing skills. VR-based practical sessions have the potential to add value to forensic science courses, through offering cost-effective practical experience, the ability to work in isolation and in a variety of different scenarios. Both user groups reported high levels of satisfaction with using the app and reports of adverse effects (motion sickness) were minimal. With reference to user feedback, we proceed to evaluate the scalability and development challenges associated with large-scale implementation of VR as an adjunct to forensic science education.     

Evaluation of amylase testing as a tool for saliva screening of crime scene trace swabs

Amylase testing has been used as a presumptive test for crime scene saliva for over three decades, mainly to locate saliva stains on surfaces. We have developed a saliva screening application for crime scene trace swabs, utilising an amylase sensitive paper (Phadebas^® Forensic Press test). Positive results were obtained for all tested dried saliva stains (0.5–32 μL) with high or intermediate amylase activity (840 and 290 kU/L). Results were typically obtained within 5 min, and all samples that produced DNA profiles were positive. However, salivary amylase activities, as well as DNA concentrations, vary significantly between individuals. We show that there is no correlation between amylase activity and amount of DNA in fresh saliva. Even so, a positive amylase result indicates presence of saliva, and thereby presence of DNA. Amylase testing may be useful for screening in investigations where the number of DNA analyses is limited due to cost, e.g., in volume crime.     

The use of simulated crime scenes in teaching undergraduate forensic sciences: Implementing an active learning approach to forensics

Incorporating a simulated crime scene into one’s pedagogy in forensic science undergraduate courses allows students the opportunity to experience a realistic scenario while demonstrating their knowledge and enhancing their critical thinking skills. The purpose of this paper is to examine an active learning approach to using simulated crime scenes to provide an impactful learning experience for students. While potentially challenging for the instructor, constructing a crime scene scenario can provide students with hands-on practical experience while helping to dispel forensic science misconceptions. Through many years of creating crime scenes, best practices for using such high impact activities in forensic science courses are described in detail, including preparatory exercises that culminate in the final crime scene scenario, considerations in preparing and constructing a crime scene activity, and supervising and assessing students once the activity begins. Three major challenges to implementing active learning exercises such as simulated crime scenes in undergraduate forensic science programs include high workload for instructors, limited supplies, and lack of suitable facilities. Workload solutions include instructors and departments considering the cost and benefit of course releases to improve curriculum and student enrollment. Supplies and facilities solutions involve innovation in reuse and repurposing of supplies, and instructor flexibility in using classroom and outdoor spaces.     

152例火场尸体的法医学检验分析

目的 探讨火场尸体的法医学检验特点及其鉴定。方法 对86起火场中152例尸体的相关检验资料进行回顾性研究。结果 152例火场尸体,生前烧死109例,纵火焚尸38例,无明显高温作用的尸体5例。主要死因有“烧死综合征”100例,火场有毒气体中毒8例,机械性损伤32例(含高坠死4例),机械性窒息5例,电击、服毒各1例;不能确定死因5例。自杀5例,他杀40例,意外107例。在生前烧死尸体,87例呼吸道内有炭末沉着,71例皮肤局部烧伤边缘组织有红肿,46例检见水泡,17例有“闭眼反应”征象,大部分尸体血中HbCO浓度超过20％;纵火焚尸少见或不见上述改变。结论 检验火场尸体,根据烧死尸体征象和血中HbCO浓度检测,并结合火场勘验资料综合分析,其死因鉴定和死亡方式推断结论方能准确。     

The potential of digital technologies in problem-based forensic learning activities

Forensic practice is the concluding practical course of the forensic science bachelor program at the School of Criminal Justice of the University of Lausanne. Learning activities are constructed around five main objectives for the resolution of simulated forensic case problems: 1) select relevant traces and items to be collected at the scene and perceive their potential value in the reconstruction process, 2) apply appropriate detection techniques in sequence to obtain clues of good quality, 3) process traces using Analysis, Comparison, Evaluation and Verification (ACE-V) methodology, 4) produce and summarise information in oral and written forms to help an investigation, and 5) work collaboratively to benefit from the diversity of group members. Simulating and supervising realistic activities is a complex task that became more and more challenging with a continuously increasing number of students over the years (from ca. 30 in 2016 to more than 60 in 2021). Thus, an educational innovation project was launched and aimed at implementing digital technologies to support the teaching staff. A computer-based crime scene simulation tool (allowing students to visualize 360° crime scenes and relevant items) and a communication tool (to simplify and centralise the communication between the students and the teaching staff) were implemented. This article describes the implementation, added value and limitations of these digital technologies in problem-based learning activities. Prior to 2020, the practical course forensic practice was delivered entirely on-site without specific technologies, and entirely on-line in 2020 (due to the sanitary restrictions related to the COVID-19 pandemic). Finally, in 2021, on-line and on-site activities were implemented with success, combining the best of both approaches in a blended teaching mode. An overall increase in the satisfaction of students and teaching staff was observed with the implementation of these tools. Limiting presence on-site allowed students to take a step back from the activities and collected items. This promoted critical thinking, and together with an increase in structured (on-line and on-site) interactions allowed for a positive, continuous learning experience. While the evaluations of these novel technologies were very positive, students still expressed their willingness to perform certain tasks on-site and a preference for face-to-face interactions.     

假说在现场勘查中的应用

综述了假说的特征和演化过程。通过案例论述假说作为逻辑推理方法之一在现场勘查中应用于死亡方式和伪装现场等的推断常起到事半功倍的效果。从一个侧面说明,刑事技术人员的专业技术固然重要,但严密的逻辑思维同样不可缺。     

Swedish crime scene technicians: facilitations,epistemic frictions and professionalization from the outside

ABSTRACT

This article investigates the role of crime scene technicians in the Swedish criminal justice system, and particularly how Swedish crime scene technicians not only examine crime scenes but also facilitate the criminal justice system’s joint production of forensic evidence. It proposes thinking about the criminal justice system as a conglomeration of epistemic cultures, that is, of communities with different ways of producing and understanding forensic evidence. Such a perspective makes it possible to understand interprofessional frictions as epistemic frictions as well as to draw attention to the facilitations, mediations and translations that crime scene technicians perform. This perspective also makes it possible to illuminate how the crime scene technicians’ professionalization – a professionalization from the outside – affects both their future crime scene work and their facilitations.     

Real-time forensic DNA analysis at a crime scene using a portable microchip analyzer

An integrated lab-on-a-chip system has been developed and successfully utilized for real-time forensic short tandem repeat (STR) analysis. The microdevice comprises a 160-nL polymerase chain reaction reactor with an on-chip heater and a temperature sensor for thermal cycling, microvalves for fluidic manipulation, a co-injector for sizing standard injection, and a 7-cm-long separation channel for capillary electrophoretic analysis. A 9-plex autosomal STR typing system consisting of amelogenin and eight combined DNA index system (CODIS) core STR loci has been constructed and optimized for this real-time human identification study. Reproducible STR profiles of control DNA samples are obtained in 2 h and 30 min with ≤0.8 bp allele typing accuracy. The minimal amount of DNA required for a complete DNA profile is 100 copies. To critically evaluate the capabilities of our portable microsystem as well as its compatibility with crime scene investigation processes, real-time STR analyses were carried out at a mock crime scene prepared by the Palm Beach County Sheriff's Office (PBSO). Blood stain sample collection, DNA extraction, and STR analyses on the portable microsystem were conducted in the field, and a successful “mock” CODIS hit was generated on the suspect's sample within 6 h. This demonstration of on-site STR analysis establishes the feasibility of real-time DNA typing to identify the contributor of probative biological evidence at a crime scene and for real-time human identification.     

Digital evidence and the crime scene

Many criminal investigations maintain an element of digital evidence, where it is the role of the first responder in many cases to both identify its presence at any crime scene, and assess its worth. Whilst in some instances the existence and role of a digital device at-scene may be obvious, in others, the first responder will be required to evaluate whether any ‘digital opportunities’ exist which could support their inquiry, and if so, where these are. This work discusses the potential presence of digital evidence at crime scenes, approaches to identifying it and the contexts in which it may exist, focusing on the investigative opportunities that devices may offer. The concept of digital devices acting as ‘digital witnesses’ is proposed, followed by an examination of potential ‘digital crime scene’ scenarios and strategies for processing them.     

The place of a forensic archaeologist at a crime scene involving a buried body

This paper examines the place that forensic archaeologists should hold at scenes of crime where a body has been buried. The forensic archaeologist is rapidly becoming a key player whose specialty should be explained, and role defined. A high level of interaction between the forensic archaeologist and other personnel implies good communications skills as well as a precarious mix of receiving orders, assistance and advice as well as giving directions to other staff. The extent to which each of these should be applied will be discussed as well as underlying the absolute need for forensic archaeologist to attend these types of scenes.     

Inference structures for crime analysis and intelligence: the example of burglary using forensic science data

There has been much work dedicated to crime analysis and intelligence in recent times. Independently, physical evidence has shown great potential for linking crimes and bringing solid informative data through the increased use of multiple databases. However, their informative potential is still often underestimated and has been poorly integrated into police information systems. We propose a framework that fully introduces this data into an intelligence based system. This framework is built on the study of inference structures extracted from investigators’ every day implicit reasoning processes. Five specific inferences are studied with the particular problem of serial burglary investigation across independent police and legal structures. On the basis of such an analytical approach, a computer prototype has been designed; it has shown great promise and has resulted in several operational successes.     

A broken system? Examining the perilous state of quality assurance in crime scene practice

Quality assurance in crime scene practice is an underdeveloped and underexamined field despite the cruciality attributed to scene work in achieving criminal justice goals. Formulation of robust strategies has been a shortcoming of oversight bodies, with a marked history of failure to address scene-specific requirements. This paper explores quality assurance mechanisms in the United Kingdom (UK) in order to uncover the longstanding status quo, and sustained challenges facing quality control regimes both on an organisational and personal level. Recommendations on a change in policy, implementation and philosophy are examined to assist with the formulation of effective quality assurance schemes in crime scene practice and align it closer to its laboratory counterparts.     

Geomatic techniques in forensic science: A review

The purpose of this review paper is to highlight various geomatic techniques that crime scene reconstructionists or forensic practitioners can use to document different kinds of scenes, highlighting the advantages, disadvantages, and when best to use each technology. This paper explores geomatic techniques such as a total station, photogrammetry, laser scanners and structured light scanners and how they can be used to reconstruct crime scenes. The goal of this paper is not to discredit manual methods, as they are long standing and reliable, but instead to shed light on alternative methods that may produce equally or more accurate results with a more visually appealing final product. It is important for law enforcement and forensic professionals to understand the advantages and disadvantages of each technique, knowing when certain techniques should be used (and when they should not), and being able to revert to traditional methods if required.     

Evaluation of the rapid analyte measurement platform (RAMP) for the detection of Bacillus anthracis at a crime scene

The aim of this study was to evaluate the accuracy and reliability of the rapid analyte measurement platform (RAMP) for presumptive identification of Bacillus anthracis spores. Test samples consisted of serial dilutions of spore preparations of several Bacillus species, including B. anthracis, which were tested, using the RAMP Anthrax test cartridge, according to the manufacturer's instructions. The fluorescence labelled antibody-antigen complexes were detected in the portable reader after 15 min following sample addition. Dilutions of common environmental and household powders were also tested to identify possible false positive results. B. anthracis spores were identified reliably in test samples containing more than 6000 spores. The test kits were highly specific, showing no cross reactivity with other Bacillus species or any environmental powders tested. The RAMP system for detection of B. anthracis spores, from environmental samples, showed consistent results under a variety of analytical conditions, enabling the trained user to provide a rapid, accurate preliminary risk assessment of a suspected bioterrorism incident.     

Ghosting phenomenon in static and dynamic footprints in India and the United States

Ghosting is the phenomenon that exists when a footprint has a lighter area around the tip of one or more toes or a shadow-like area at the back of the heel. To date, ghosting has been considered primarily a finding of dynamic (walking) footprints, rather than static (standing) footprints. The prevalence of ghosting in static footprints is unknown, and research on its presence in static and dynamic footprints from the same participant is sparse, as are studies on its occurrence in different geographic populations. This study is among the first to evaluate the occurrence of ghosting in the static and dynamic footprints from a particular individual with participants in two geographic populations.A combination of both inkless and ink footprint collection systems were used to obtain a total of 206 bare footprints from 103 adult participants from the United States and India. The data comprised 103 static and 103 dynamic footprints.Ghosting occurred significantly in static footprints, though less frequently than in dynamic footprints. Ghosting in static footprints was seen most often at the first toe, followed by the third and second respectively. This aspect appeared least at the heel. In dynamic footprints, it occurred most at the first toe, followed by the second and fourth toes, and then the third toe and the heel. The prevalence of ghosting in footprints from the United States and India differed in their locations, notably at the first and second toes in the static footprints and at the heel in the dynamic footprints.