Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Macziewski, B S Chad; Spotts, Ryan; Chumbley, Scott

doi:10.1111/1556-4029.13342

Cited by 9 publications

(6 citation statements)

References 5 publications

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“…During the last two decades, new innovative 3D surface topological scanning microscopy has been developed with the potential to improve physical matching. Different 3D acquisition systems, employing 3D laser scanners, optical coherence tomography, stylus scanning instruments, and confocal microscopy, have been utilized for forensic evidence identification applications [19,26,29‐43]. Automated surface acquisition and matching processes utilizing 3D topography data have demonstrated promising improvements in the objectivity of the comparison process [34].…”

Section: Introductionmentioning

confidence: 99%

“…During the last two decades, new innovative 3D surface topological scanning microscopy has been developed with the potential to improve physical matching. Different 3D acquisition systems, employing 3D laser scanners, optical coherence tomography, stylus scanning instruments, and confocal microscopy, have been utilized for forensic evidence identification applications [19,26,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

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Quantitative matching of forensic evidence fragments utilizing 3D microscopy analysis of fracture surface replicas

Dawood

Llosa-Vite

Thompson

et al. 2022

Journal of Forensic Sciences

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Silicone casts are widely used by practitioners in the comparative analysis of forensic items. Fractured surfaces carry unique details that can provide accurate quantitative comparisons of forensic fragments. In this study, a statistical analysis comparison protocol was applied to a set of 3D topological images of fractured surface pairs and their replicas to provide confidence in the quantitative statistical comparison between fractured items and their silicone cast replicas. A set of 10 fractured stainless steel samples were fractured from the same metal rod under controlled conditions and were replicated using a standard forensic casting technique. Six 3D topological maps with 50% overlap were acquired for each fractured pair. Spectral analyses were utilized to identify the correlation between topological surface features at different length scales of the surface topology. We selected two frequency bands over the critical wavelength (greater than two‐grain diameters) for statistical comparison. Our statistical model utilized a matrix‐variate t‐distribution that accounts for overlap between images to model match and non‐match population densities. A decision rule identified the probability of matched and unmatched pairs of surfaces. The proposed methodology correctly classified the fractured steel surfaces and their replicas with a posterior probability of match exceeding 99.96%. Moreover, the replication technique shows potential in accurately replicating fracture surface topological details with a wavelength greater than 20 μm, which far exceeds the feature comparison range on most metallic alloy surfaces. Our framework establishes the basis and limits for forensic comparison of fractured articles and their replicas while providing a reliable fracture mechanics‐based quantitative statistical forensic comparison.

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Section: Introductionmentioning

confidence: 99%

“…During the last two decades, new innovative 3D surface topological scanning microscopy has been developed with the potential to improve physical matching. Different 3D acquisition systems, employing 3D laser scanners, optical coherence tomography, stylus scanning instruments, and confocal microscopy, have been utilized for forensic evidence identification applications [19,26,[29][30][31][32][33][34][35][36][37][38][39][40][41][42][43].…”

Section: Introductionmentioning

confidence: 99%

Quantitative matching of forensic evidence fragments utilizing 3D microscopy analysis of fracture surface replicas

Dawood

Llosa-Vite

Thompson

et al. 2022

Journal of Forensic Sciences

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“…In addition, it has been applied to characterise biological samples that are not amenable to confocal microscopy due to their opacity, such as teeth and bones. This technology has been used in a medical context [15,17,18], as well as in the analysis of archaeological and anthropological samples [19][20][21][22][23][24] and even in the comparison of toolmarks in a forensic context [25][26].…”

Section: Introductionmentioning

confidence: 99%

Investigation of infinite focus microscopy for the determination of the association of blood with fingermarks

et al. 2018

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The determination of the type of deposition mechanism of blood within fingermarks at the scene of violent crimes is of great importance for the reconstruction of the bloodshed dynamics. However, to date, evaluation still relies on the subjective visual examination of experts. Practitioners encounter three types of scenarios in which blood may be found in fingermarks and they refer to the following three deposition mechanisms: (i) blood marks, originating from a bloodied fingertip; (ii) marks in blood, originating from a clean fingertip contacting a blood contaminated surface; (iii) coincidental deposition mechanisms, originating from a clean fingertip contacting a clean surface, leaving a latent fingermark, and subsequent contamination with blood.. The authors hypothesised that, due to differences in distribution of blood in the furrows and on the ridges, the height of blood depositions on the ridges and furrows (and their relative proportions), will differ significantly across the three depositions mechanisms. A second hypothesis was made that the differences would be significant and consistent enough to exploit their measurement as a quantitative and objective way to differentiate the deposition mechanisms. In recent years, infinite focus microscopy (IFM) has been developed, allowing for the computational generation of a 3D image of the topology of a sample via acquisition of images on multiple focal planes. On these bases, it was finally hypothesised that the application of this technique would allow the distinction of deposition mechanisms (i) to (iii) A set of preliminary experiments were designed to test whether IFM was "fit for purpose" and, subsequently, to test if any of the three deposition mechanisms scenarios could be differentiated. Though IFM enabled the analysis of tape lifted samples with some success, for samples produced and analysed directly on the surface of deposition, the results show that the measurements from any scenario will be highly dependent on the original surface of deposition (both in terms of its nature and of the variable exposure to environment); as crime scenes exhibit a wide range of possible relevant surfaces of deposition, the technique showed to not have the desired wide appeal for inclusion into a standardised set of protocols within a routine crime scene workflow.

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“…These measurements can be used in place of the direct physical specimen. Several previous works have used 3D measurements to study striated and impressed toolmarks as well as toolmarks produced by firearms on fired ammunition components (4)(5)(6)(7)(8)(9).…”

mentioning

confidence: 99%

Development and Validation of a Virtual Examination Tool for Firearm Forensics, ,

Duez¹,

Weller²,

Brubaker

et al. 2017

Journal of Forensic Sciences

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The transition from 2D imaging to 3D scanning in the discipline of firearms and toolmark analysis is likely to provide examiners an unprecedented view of microscopic surface topography. The digital examination of measured 3D surface topographies has been referred to as virtual microscopy (VM). The approach offers several potential advantages over traditional comparison microscopy. Like any new analytic method, VM must be validated prior to its use in a crime laboratory. This paper describes one of the first validation studies of virtual microscopy. Fifty-six participants at fifteen laboratories used virtual microscopic tools to complete two proficiency-style tests for cartridge case identification. All participating trained examiners correctly reported 100% of the identifications (known matches) while reporting no false positives. The VM tools also allowed examiners to annotate compared surfaces. These annotations provide insight into the types of marked utilized in comparative analysis. Overall, the results of the study demonstrate that trained examiners can successfully use virtual microscopy to conduct firearms toolmark examination and support the use of the technology in the crime laboratory.

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Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Cited by 9 publications

References 5 publications

Quantitative matching of forensic evidence fragments utilizing 3D microscopy analysis of fracture surface replicas

Quantitative matching of forensic evidence fragments utilizing 3D microscopy analysis of fracture surface replicas

Investigation of infinite focus microscopy for the determination of the association of blood with fingermarks

Development and Validation of a Virtual Examination Tool for Firearm Forensics, ,

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