Tracers as invisible evidence — The transfer and persistence of flock fibres during a car exchange

Slot, Ana; Weerd, Jaap van der; Roos, Martin; Baiker, Martin; Stoel, Reinoud D.; Zuidberg, M.

doi:10.1016/j.forsciint.2017.03.005

Cited by 14 publications

(5 citation statements)

References 5 publications

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“…Studies which utilise fluorescent proxies tend to follow similar methodologies; the fluorescent material is introduced to a surface, imaged repeatedly during the experiment, and the resultant images are segmented and analysed. At present, there does not appear to be a standardised methodology for segmenting images in the context of persistence studies which employ a fluorescent proxy, but most appear to involve a form of thresholding (Table ; (e.g., ). Where it is explicit that thresholding has been used to segment the images (e.g., ) it is not readily apparent whether the threshold value was manually defined or calculated with an algorithm (Table ).…”

Section: Examples Of the Methodologies Used To Process Imagery From Pmentioning

confidence: 99%

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A Comparison of Thresholding Methods for Forensic Reconstruction Studies Using Fluorescent Powder Proxies for Trace Materials

Levin

Morgan

Griffin

et al. 2018

Journal of Forensic Sciences

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Image segmentation is a fundamental precursor to quantitative image analysis. At present, no standardised methodology exists for segmenting images of fluorescent proxies for trace evidence. Experiments evaluated (i) whether manual segmentation is reproducible within and between examiners (with three participants repeatedly tracing three images) (ii) whether manually defining a threshold level offers accurate and reproducible results (with 20 examiners segmenting 10 images), and (iii) whether a global thresholding algorithm might perform with similar accuracy, while offering improved reproducibility and efficiency (16 algorithms tested). Statistically significant differences were seen between examiners’ traced outputs. Manually thresholding produced good accuracy on average (within ±1% of the expected values), but poor reproducibility (with multiple outliers). Three algorithms (Yen, MaxEntropy, and RenyiEntropy) offered similar accuracy, with improved reproducibility and efficiency. Together, these findings suggest that appropriate algorithms could perform thresholding tasks as part of a robust workflow for reconstruction studies employing fluorescent proxies for trace evidence.

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Section: Examples Of the Methodologies Used To Process Imagery From Pmentioning

confidence: 99%

“…Subsequently, adding up all the foreground pixels and dividing them by the estimated number of pixels per fibre, yielded the amount of fibres on an image." (Slot et al [7]: 181)…”

Section: Evaluating Reproducibilitymentioning

confidence: 99%

A Comparison of Thresholding Methods for Forensic Reconstruction Studies Using Fluorescent Powder Proxies for Trace Materials

Levin

Morgan

Griffin

et al. 2018

Journal of Forensic Sciences

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“…Empirical studies addressing the transfer and persistence of trace materials have developed since the early work of Pounds and Smalldon () (fibers), Brewster, Thorpe, Gettinby, and Caddy () and Hicks, Vanina, and Margot () (glass), and Morgan et al () and Bull, Morgan, Sagovsky, and Hughes () (general particulates). There is now a growing body of published work that addresses a wide range of different physical traces (Bitter, (smoke residues), Maitre et al, (GSRs), Palmer, Sheridan, Puckett, Richardson, & Lo, and Slot et al, (fibers), Levin, Morgan, Scott, & Jones, (diatoms), Morgan, Scott, Ainley, & Bull, (soils) Morgan, Flynn, et al, , and Morgan, Allen, King, & Bull, (pollen)).…”

Section: Understanding Trace Materialsmentioning

confidence: 99%

Crime reconstruction and the role of trace materials from crime scene to court

Morgan

Meakin

French

et al. 2019

WIREs Forensic Science

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Crime reconstruction takes place in a complex ecosystem and needs to be responsive to the context of each case. For accurate, reproducible and transparent crime reconstructions to take place, a holistic approach is needed that considers the different stakeholders, different types of trace material, integral human decision-making and interconnected nature of the forensic science process. For robust reconstruction, there needs to be a consideration of both the distinctive types of trace material that can contribute to the reconstruction, and an understanding of the interplay of human decision-making within reconstruction approaches. In addition, it is also necessary to consider source attribution of a trace material in addition to the activities that led to the generation, identification, transfer, and persistence of the trace. This requires explicit and tacit forms of knowledge, and an incorporation of the inherent uncertainty and risk in the reconstruction approach. The communication of conclusions reached in a crime reconstruction that address what the evidence means is also an important consideration given the different requirements of intelligence and evidence. Therefore, undertaking a crime reconstruction within a holistic framework that seeks to incorporate the complexity of the forensic science ecosystem is valuable for achieving a problem solving approach that offers reproducible, transparent reconstructions with a clear articulation of risk and uncertainty that can be of value to investigators and the courts.

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“…Such interpretation partly relies on the existence of transfer and persistence models on the amount of silicone transferred from a condom into the vaginal matrix and the degradation kinetics with time. These models, as described in literature regarding other types of evidence [16][17][18][19][20], usually rely on the quantification of the target compound or trace material. There is hence a need for quantification studies of silicone traces, validated according to ISO17025 norms, so that transfer and persistence questions relating to condom evidence can be addressed.…”

Section: Introductionmentioning

confidence: 99%

Negative results: Investigations into the quantification of silicone-based condom lubricants in solution by DRIFTS-FTIR

Burnier

Monzò

Sauzier

et al. 2022

Forensic Science International: Reports

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Tracers as invisible evidence — The transfer and persistence of flock fibres during a car exchange

Cited by 14 publications

References 5 publications

A Comparison of Thresholding Methods for Forensic Reconstruction Studies Using Fluorescent Powder Proxies for Trace Materials

A Comparison of Thresholding Methods for Forensic Reconstruction Studies Using Fluorescent Powder Proxies for Trace Materials

Crime reconstruction and the role of trace materials from crime scene to court

Negative results: Investigations into the quantification of silicone-based condom lubricants in solution by DRIFTS-FTIR

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