Comparison of screwdriver tips to the resultant toolmarks

Kidd, Julie Ann

doi:10.31274/rtd-180813-15731

Cited by 4 publications

(4 citation statements)

References 7 publications

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“…The tips were of the flat‐head type and were collected and certified by the company to have been sequentially made and ground. Details concerning the tips used, their manufacture and acquisition can be found elsewhere . Both sides of each screwdriver tip were used to make test marks at vertical angles of 40, 55, and 70°, as well as at horizontal rotation angles of 0, 10, 20, and 30°.…”

Section: Methodsmentioning

confidence: 99%

Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Macziewski

Spotts

Chumbley

2016

Journal of Forensic Sciences

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Numerous studies have focused on determining whether objective statistical methods can be used to discriminate between known matches and nonmatches when comparing laboratory prepared toolmarks. This study involved an analysis of striated toolmarks made as a function of varying vertical and horizontal angles of attack. Comparisons based on experimental data show that replicate toolmarks from the same tool show high correlation values at identical vertical and horizontal angles, with the correlation decreasing as the angular difference increases, especially for horizontal angular changes. Comparisons between nonmatching samples produce low correlation values that remain unchanged as horizontal angular differences increase. While complete statistical separation was not achieved between matching and nonmatching samples, there is evidence demonstrating that toolmarks can be identified if the variation in horizontal angle is within 10°. The experiment shows that computer-aided comparison techniques could be viable for identification with the proper statistical algorithm.

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Section: Methodsmentioning

confidence: 99%

Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Macziewski

Spotts

Chumbley

2016

Journal of Forensic Sciences

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“…The IFM was chosen because of its ability to accurately measure the microscale surface roughness of a screwdriver tip. Several competing screwdriver tip imaging methods were investigated in , and the IFM emerged as the only viable option. This is due to the basic operating principle of the focus variation technique.…”

Section: Methodsmentioning

confidence: 99%

Virtual Tool Mark Generation for Efficient Striation Analysis^,

Ekstrand

Zhang

Grieve

et al. 2014

Journal of Forensic Sciences

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This study introduces a tool mark analysis approach based upon 3D scans of screwdriver tip and marked plate surfaces at the micrometer scale from an optical microscope. An open-source 3D graphics software package is utilized to simulate the marking process as the projection of the tip's geometry in the direction of tool travel. The edge of this projection becomes a virtual tool mark that is compared to cross-sections of the marked plate geometry using the statistical likelihood algorithm introduced by Chumbley et al. In a study with both sides of six screwdriver tips and 34 corresponding marks, the method distinguished known matches from known nonmatches with zero false-positive matches and two false-negative matches. For matches, it could predict the correct marking angle within ±5-10°. Individual comparisons could be made in seconds on a desktop computer, suggesting that the method could save time for examiners.

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“…These surfaces require a system capable of making accurate micro-and nanoscale measurements of surfaces at a high angle to the detector. A previous thesis had located such a system (Kidd, 2007). Given the relative complexity of the screwdriver head, this system should be able to accurately scan any other tool as well.…”

Section: Proposed Approachmentioning

confidence: 99%

Virtual tool mark generation for efficient striation analysis in forensic science

Ekstrand

2012

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Comparison of screwdriver tips to the resultant toolmarks

Cited by 4 publications

References 7 publications

Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Virtual Tool Mark Generation for Efficient Striation Analysis^,

Virtual tool mark generation for efficient striation analysis in forensic science

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Comparison of screwdriver tips to the resultant toolmarks

Cited by 4 publications

References 7 publications

Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Validation of Toolmark Comparisons Made At Different Vertical and Horizontal Angles

Virtual Tool Mark Generation for Efficient Striation Analysis,

Virtual tool mark generation for efficient striation analysis in forensic science

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Product

Resources

About

Virtual Tool Mark Generation for Efficient Striation Analysis^,