The effect of different imaging techniques for the visualisation of evidence in court on jury comprehension

Forensic applications of 3D printing - a review of literature, case studies and future implications

The technological revolution has impacted every facet of life, including crime and law enforcement. Following the adoption of digital evidence, artificial intelligence, and CT scans, scientists and legal professionals have now turned to three-dimensional (3D) printing to present evidence more clearly in a court of law. 3D printing is a process of creating physical objects by depositing materials layer by layer, based on digital models, to form solid, tangible replicas. It has a wide range of applications across various fields of forensic science, including explosives analysis, ballistics, forensic medicine, forensic archaeology, and crime scene reconstruction. 3D printed impression evidence such as tire marks, and shoe prints etc., offers more detailed and accurate representations compared to traditional methods. Similarly, 3D printed crime scene reconstructions provide immersive and precise visualizations, enhancing their reliability and utility in forensic investigations. This article discusses the steps involved in 3D printing, the types of 3D printing technologies, its applications in various forensic examinations, and real-world criminal cases that highlight the significance of 3D printed evidence in judicial decision-making. 3D printing has proven instrumental in these cases for establishing the linkage of weapons to crimes and correlating injuries to weapons, and identifying charred or mutilated remains. However, like any emerging technology, 3D printing in forensics faces certain challenges, which need to be addressed to maximize its potential. These include standardized protocols, ethical considerations, and high initial setup costs-all of which must be addressed to fully realize its potential.

Evaluating juror understanding of traumatic head injury with different formats of evidence presentation in court: a follow up study

Jurors rely on evidence presented in court to find the facts of a case. Consequently, the manner in which evidence is delivered may significantly impact the extent to which jurors comprehend and interpret the evidence. Building on a pilot study, the aim of this research was to further investigate which format for presenting forensic medical evidence in court was best for laypersons (i.e., jurors) to understand. This study presented a forensic medical testimony detailing a head injury to members of the community who had been called for jury duty. The evidence was presented using six different formats: verbal, autopsy photo, colour coded cross-sectional computed tomography (CT) image, volume rendered CT, three-dimensional (3D) print and interactive technology. Jurors found autopsy photographs to be more confronting than any other format. Verbal evidence was found to be the most complicated to understand, with volume rendered CT, the 3D print and interactive court technology being the least complicated. Jurors considered the 3D print easiest to understand, however when asked about the cause of the injuries, cause of death and severity of injuries, they showed there understanding was limited and the presentation format made little difference. These findings indicate that forensic medical evidence is inherently complex for a layperson to fully comprehend, regardless of the presentation format.

Single-camera photogrammetry using a mobile phone for low-cost documentation of corpses

Photogrammetry is a technique for studying and defining objects' shape, dimension, and position in a three-dimensional space using measurements obtained from two-dimensional photographs. It has gained popularity following the development of computer graphics technologies and has been applied to various branches of medicine. In this study, the authors present a method for low-cost photorealistic documentation of corpses during autopsy using single-camera photogrammetry with a mobile phone. Besides representing the body by demonstrating the injured and non-injured body parts as control, evidencing the body parts on a 3D reconstruction allows easy explanation to nonmedical experts such as lawyers.

3D scanning a crime scene to enhance juror understanding of Bloodstain Pattern Analysis evidence

There are numerous crime scene investigation applications of 3D scanning that have been previously documented. This paper documents the application of a 3D point cloud in the presentation of Bloodstain Pattern Analysis evidence to mock jurors. 150 mock jurors viewed a presentation of Bloodstain Pattern Analysis evidence from a murder trial in the UK. After viewing the evidence, the participants were tested on their knowledge of the evidence and repeated the test again 2 weeks later; to simulate criminal trial conditions; whereby there is a time lapse between the initial viewing of evidential material and deliberation. This paper found that the mock jurors who additionally viewed a 3D flythrough of a point cloud of the crime scene, better retained knowledge of the evidence over time, reported a greater ability to visualise the crime scene and had higher levels of interest in the evidence. Crucially, the 3D flythrough group did not report different levels of confidence in the accuracy of their memories of the evidence, nor different levels of emotional arousal to the group that viewed the evidence without the 3D presentation. Together, these findings suggest that 3D scanning of crime scenes, and the resultant point cloud's presentation to jurors, could add further value to the justice system when spatial information, such as Bloodstain Pattern Analysis evidence, is presented.

3D printed skulls in court - a benefit to stakeholders?

Forensic pathologists may use 3D prints as demonstrative aids when providing expert testimony in court of law, but the effects remain unclear despite many assumed benefits. In this qualitative study, the effects of using a 3D print, demonstrating a blunt force skull fracture, in court were explored by thematic analysis of interviews with judges, prosecutors, defence counsels, and forensic pathologists with the aim of improving the expert testimony. Five semi-structured focus groups and eight one-to-one interviews with a total of 29 stakeholders were transcribed ad verbatim and analysed using thematic analysis. The study found that a highly accurate 3D print of a skull demonstrated autopsy findings in detail and provided a quick overview, but sense of touch was of little benefit as the 3D print had different material characteristics than the human skull. Virtual 3D models were expected to provide all the benefits of 3D prints, be less emotionally confronting, and be logistically feasible. Both 3D prints and virtual 3D models were expected to be less emotionally confronting than autopsy photos. Regardless of fidelity, an expert witness was necessary to translate technical language and explain autopsy findings, and low-fidelity models may be equally suited as demonstrative aids. The court infrequently challenged the expert witnesses' conclusions and, therefore, rarely had a need for viewing autopsy findings in detail, therefore rarely needing a 3D print.

A survey of case studies on the use of forensic three-dimensional printing in England and Wales

3D printing has rapidly developed and been applied in forensic science due to its use in creating demonstrations for courts of law. Much of the literature on this specific topic has focused on the use of 3D printed models in academia, the potential influence on a jury, and its use as a long-term documentation process, but with few actual forensic case examples. This paper offers an insight into the development of 3D printing in forensic practice and how 3D printing is currently being used in the criminal justice system in England and Wales.

A series of case reports were gathered from multiple police forces and forensic practitioners in the UK to identify how 3D printing was being used. These discussions established who was requesting 3D printed exhibits, what type of technologies were being utilised, what type of exhibits were being printed, and resulting feedback for the use of 3D printed material within a criminal case. As a result, this research demonstrates the current use of 3D printing in England and Wales, discussing the associated cases that have been known to incorporate 3D prints. Likewise, this work explores the limitations that have been encountered by forensic practitioners and identifies a series of research questions that should be considered in future investigations.

A multi-method assessment of 3D printed micromorphological osteological features

The evaluation of 3D printed osteological materials has highlighted the difficulties associated with accurately representing fine surface details on printed bones. Moreover, there is an increasing need for reconstructions to be demonstrably accurate and reliable for use in the criminal justice system. The aim of this study was to assess the surface quality of 3D prints (n = 9) that presented with micromorphological alterations from trauma, taphonomy and pathology processes. The archaeological bones were imaged using micro-CT scanning and 3D printed with selective laser sintering (SLS) printing. A multi-method experimental approach subsequently identified: (1) the 3D printed bones to be metrically accurate to within 1.0 mm; (2) good representation of micromorphological surface features overall, albeit with some loss of intricate details, depths, and fine textures that can be important for visual processing; (3) five of the nine 3D printed bones were quantitatively scored as accurate using the visual comparison method; and, (4) low mesh comparison distances (± 0.2 mm) between the original models and the digitised 3D print models. The findings offer empirical data that can be used to underpin 3D printed reconstructions of exhibits for use in courts of law. In addition, an adaptable pathway was presented that can be used to assess 3D print accuracy in future reconstructions.

A systematic review of 3D scanners and computer assisted analyzes of bite marks: searching for improved analysis methods during the Covid-19 pandemic

The global Covid-19 pandemic has forced forensic dentists to improve infection control methods. This search investigated the practical utilization of different 3D scanners to record and to analyze bite marks in the skin- and inanimate objects with this aim in mind. A systematic review of the literature using keywords like "human bite mark", "bite mark analyzes", "3D analyzes", "3D scanning", "forensic odontology", and "forensic dentistry" was performed in three scientific databases: MEDLINEOvid®, Pubmed® and Google Scholar. The initial search yielded 263 full-text articles, of which 15 were considered eligible and current within the last 10 years. 3D scanners and computer-assisted human bite mark analyzes showed potential advantages and can be effectively used in forensic odontology on skin and inanimate objects. These technologies minimize the number of people being exposed to pathogens, simplify the chain of evidence, facilitate immediate information exchange between the team members and enable the virtual presentation of the expert witnesses in a court of law.

3D forensic science: A new field integrating 3D imaging and 3D printing in crime reconstruction

3D techniques are increasingly being used by forensic scientists in crime reconstruction. The proliferation of 3D techniques, such as 3D imaging and printing being employed across the various stages of the forensic science process, means that the use of 3D should be considered as a distinct field within forensic science. '3D Forensic Science' ('3DFS') is therefore presented in this paper as a field that brings together a range of 3D techniques and approaches that have been developed within different areas of forensic science for achieving crime reconstructions and interpreting and presenting evidence. It is argued that by establishing this distinct field, defining its boundaries, and developing expertise, best practice and standards, the contribution of 3DFS to the criminal justice system can be maximised and the accuracy and robustness of crime reconstruction endeavours can be enhanced.

Assessment of the accuracy of 3D printed teeth by various 3D printers in forensic odontology

Additive manufacturing technology has benefited many sectors, and its use in forensic sciences has opened up a variety of new opportunities for analysing and exhibiting forensic materials. However, to perform analytical procedures on 3D printed bones and teeth in forensic odontology, the metric and morphological precision of the printed replicas must first be validated. To address this, the present study was undertaken using 12 extracted human teeth that were 3D printed using five different techniques. Manual measurements and a digital mesh comparison were used to evaluate the metric precision of all samples. The findings showed that the printed replicas were accurate to within 0.5 mm of the actual teeth. It was suggested that Digital Light Processing (DLP) prints be used for potential forensic odontology applications based on measurements, digital comparison, and ease of use.

Application of non-contact scanning to forensic podiatry: A feasibility study

Foot impression evidence recovered from crime scenes can be available in the form of barefoot prints, sock-clad footprints, or as impressions within footwear. In some cases, suspects leave their footwear at the scene of the crime, and the insoles from the footwear can be important in linking a person to the footwear. The application of 3D data-collecting technology is becoming more and more popular within forensic science and has been used to recover footwear impression evidence. The present study is a feasibility study to discover if 3D data capturing devices can be applied to insoles; to capture the footprint impression for measurement using the Gunn method (a method used in forensic podiatry casework). Three different methods of data capture were conducted; Adobe Photoshop, MeshLab, and calipers used directly on the insole. Paired t-tests and Intraclass Correlation Coefficient (ICC) were conducted for all three data capture methods. Seven measurements used in this study were significantly different across all three methods. ICC scores were moderate to excellent for the Photoshop method, poor to good for the 3D method, and moderate to excellent for the Direct method.

An Overview of 3D Printing in Forensic Science: The Tangible Third-Dimension

There has been a rapid development and utilization of three-dimensional (3D) printing technologies in engineering, health care, and dentistry. Like many technologies in overlapping disciplines, these techniques have proved to be useful and hence incorporated into the forensic sciences. Therefore, this paper describes how the potential of using 3D printing is being recognized within the various sub-disciplines of forensic science and suggests areas for future applications. For instance, the application can create a permanent record of an object or scene that can be used as demonstrative evidence, preserving the integrity of the actual object or scene. Likewise, 3D printing can help with the visualization of evidential spatial relationships within a scene and increase the understanding of complex terminology within a courtroom. However, while the application of 3D printing to forensic science is beneficial, currently there is limited research demonstrated in the literature and a lack of reporting skewing the visibility of the applications. Therefore, this article highlights the need to create good practice for 3D printing across the forensic science process, the need to develop accurate and admissible 3D printed models while exploring the techniques, accuracy and bias within the courtroom, and calls for the alignment of future research and agendas perhaps in the form of a specialist working group.