Integrated computer-aided forensic case analysis, presentation, and documentation based on multimodal 3D data

Abstract

Three-dimensional (3D) crime scene documentation using 3D scanners and medical imaging modalities like computed tomography (CT) and magnetic resonance imaging (MRI) are increasingly applied in forensic casework. Together with digital photography, these modalities enable comprehensive and non-invasive recording of forensically relevant information regarding injuries/pathologies inside the body and on its surface. Furthermore, it is possible to capture traces and items at crime scenes. Such digitally secured evidence has the potential to similarly increase case understanding by forensic experts and non-experts in court. Unlike photographs and 3D surface models, images from CT and MRI are not self-explanatory. Their interpretation and understanding requires radiological knowledge. Findings in tomography data must not only be revealed, but should also be jointly studied with all the 2D and 3D data available in order to clarify spatial interrelations and to optimally exploit the data at hand. This is technically challenging due to the heterogeneous data representations including volumetric data, polygonal 3D models, and images. This paper presents a novel computer-aided forensic toolbox providing tools to support the analysis, documentation, annotation, and illustration of forensic cases using heterogeneous digital data. Conjoint visualization of data from different modalities in their native form and efficient tools to visually extract and emphasize findings help experts to reveal unrecognized correlations and thereby enhance their case understanding. Moreover, the 3D case illustrations created for case analysis represent an efficient means to convey the insights gained from case analysis to forensic non-experts involved in court proceedings like jurists and laymen. The capability of the presented approach in the context of case analysis, its potential to speed up legal procedures and to ultimately enhance legal certainty is demonstrated by introducing a number of representative forensic cases.

Imaging in forensic science: Five years on

“…Post-mortem CT (PMCT) is common place in several forensic institutes (Weiss et al 2017) due to its superior visualisation capabilities, however, the technique is limited in several aspects. First, it works well for visualising bones, but less so for soft tissues (Bornik et al 2018). The equipment is large and expensive (Bornik et al 2018), although there is provision of a mobile CT scanner in the UK (Rutty et al 2007).…”

“…First, it works well for visualising bones, but less so for soft tissues (Bornik et al 2018). The equipment is large and expensive (Bornik et al 2018), although there is provision of a mobile CT scanner in the UK (Rutty et al 2007). Additionally, CT scans are influenced by metal artefacts such as gunshot or dental amalgams (Bornik et al 2018), and lastly, samples must be transportable and fit inside the CT gantry.…”

“…The equipment is large and expensive (Bornik et al 2018), although there is provision of a mobile CT scanner in the UK (Rutty et al 2007). Additionally, CT scans are influenced by metal artefacts such as gunshot or dental amalgams (Bornik et al 2018), and lastly, samples must be transportable and fit inside the CT gantry. Since the technique images in slices, the quality of the models from CT is limited and affected by the scan resolution, the parameters involved in scan acquisition (Guyomarc'h et al 2012), and the user segmentation procedure (Carew et al 2018).…”

“…A recent example used a virtual animation to depict how a victim obtained their injuries, through animating a moving 3D skeleton with a bullet paths penetrating the body (Villa et al 2017). Furthermore, combining multimodal imaging with CAD has been used to show elaborate virtual representations and interactive videos of injuries and weapons (Bornik et al 2018). Incorporating CAD objects into a 3D model merges case-findings with interpretations, although useful for demonstrations the two must be clearly defined (see 3.4).…”

Virtual reality – level of immersion within the crime investigation

“…A recent example used a virtual animation to depict how a victim obtained their injuries, through animating a moving 3D skeleton with bullet paths penetrating the body [6]. Furthermore, combining multimodal imaging with CAD has been used to show elaborate virtual representations and interactive videos of injuries and weapons [7].…”