Abstract

An investigation was conducted to determine some conditions that could provide false results for muzzle-to-garment distance determinations as they are commonly conducted in a forensic laboratory. The examinations of concern were visual examinations and chemical examinations. The chemical examinations included the Modified Griess Test and the Sodium Rhodizonate Test. The conditions tested were exposure to running water, submersion in water, UV exposure, extreme cold, submersion with extreme cold, extreme heat, and partial burning. It was found that a long exposure to water would remove nitrite particles from the muzzle residues and could prevent the Modified Griess Test from being used for distance determination. None of the other conditions were found to significantly interfere with the examinations for muzzle residues and distance determinations.

Semester/Year of Award

Spring 2015

Mentor

David D. Cunningham

Department/Professional Affiliation

Chemistry

Access Options

Restricted Access Thesis

Degree Name

Honors Scholars

Department

Chemistry

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Muzzle residues observed on test cloth

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Muzzle residues next to a bullet hole observed through a stereomicroscope

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Cloth being placed on photographic paper

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Heat being applied with an iron for Modified Griess Test

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Removing the cloth from the photographic paper

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Orange coloration, indicating the presence of nitrite particles

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Sodium rhodizonate solution applied to test cloth

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Beginning of pink coloration after the application of buffer solution

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Final observed pink reaction from heavy metal residues

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Reaction of hydrochloric acid to form blue/violet color

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Orange haze present from a blank cloth

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Example of muzzle residues observed with a stereomicroscope

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Example of known positive reaction with the Modified Griess Test

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Example of known negative reaction with the Modified Griess Test

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Example of a Sodium Rhodizonate Test reaction assigned a value of 1

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Example of a Sodium Rhodizonate Test reaction assigned a value of 5

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