The non-destructive characterisation of forensic trace evidence (tool marks) from screwdrivers by scanning electron microscopy and laser ablation inductively coupled plasma mass spectroscopy

Abdulla Al-Shammari

    Research output: ThesisDoctoral Thesis

    476 Downloads (Pure)

    Abstract

    [Truncated abstract] This thesis is a compilation of five research studies examining the potential of different analysis techniques when applied to the forensic investigations of screwdriver heads and the associated damage/debris occurring when these screwdrivers are used in criminal activities. Data acquired from Optical Microscopy (OM), Scanning Electron Microscopy (SEM), and Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) is manipulated in various manners using statistical software packages and graphing software packages to exposed any hidden patterns or trends that might exist but which have not, as yet, been discovered. The initial study in Chapter 5 is a basic optical examination of different screwdriver heads / tips obtained from the Collection of Ballistics and Tool Marks at the Dubai police forensic lab. These heads/tips of the screwdrivers are examined using optical microscopy images and measurement data derived from these images is tabled. This short study serves the purpose of introducing the author to important manufacturing process aspects of screwdrivers, their assorted heads / tips and aspects of screwdriver damage that can be examined via OM. The next study in Chapter 6 primarily aims to develop an effective method to characterise screwdriver scratch marks objectively using information derived from SEM Backscattered Electron (BSE) and Secondary Electron (SE) images. Suitable screwdriver scratch test conditions are first determined to enable this characterisation process. Energy Dispersive Spectroscopy (EDS) spectrum information is obtained and examined. Following on is Chapter 7 which involved sourcing screwdrivers from 5 different countries/manufactures and subjecting these screwdrivers to SEM analysis (BSE imaging, SE imaging, EDS spectrums, and EDS element survey maps). With data from these five different countries/manufacturers cross correlation and direct comparisons was possible.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2012

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