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Toolmark Identification (Toolmark Examination (Inconclusive Results -…
Toolmark Identification
Tool Manufacture
Metal-forming Techniques - Involves the use of heat and/or pressure on metal to get it into the desired shape
Modern Machining Techniques - Some of the more modern techniques used to remove material include EDM, laser machining, ECM, etching, etc.
Cutting Operations - Involves removing a certain material with another material that is heavier and sturdier than that of the material you are cutting into
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Equipment - Some of the instruments used for comparison include the comparison microscope, the stereomicroscope, microscope lighting option and imaging equipment
Toolmark Examination
Inconclusive Results - There are a number of reasons why a comparion can be deamed inconclusive. Some of which include an impression that was made by two difference sources, the object has become too distorted for comparison or changes in the tool after a mark was made
Intercomparison - This involves comparing a tool that had been used and/or linked to multiple crimes
Comparison of Evidence Toolmarks and Test Marks - There are a number of steps that need to be taken when comparing a toolmark impresion that was found on a piece of evidence vs a toolmark impression on a test item
Production of Test Toolmarks - When trying to reproduce a toolmark, there are a number of factors that come into place to ensure proper testing is done
Intercomparison of Fractured Objects - A method used to compare fractured items is a reverse lighting technique
Microscopic Comparisons - When using a microscope for comparsions, it is vital that the microscope is calibrated and the proper objective is used for visualization
Reverse Lighting Technique - There are a number of steps that need to be taken into consideration when using the reverse lighting technique. One instant in which this technique can be used is for fractured bomb components
Microscopic Procedures - The basic procedure involves filling out a chain of custody, following lab protocols, examining for trace evidence, determining the presence of toolmark impressions
Dillon, H. John. “Module 13 :: Toolmark Identification” Firearm Examiner Training, projects.nfstc.org/firearms/.