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Chemical Analysis of Firearm Discharge Residues Using Laser Induced Breakdown Spectroscopy

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Chemical Analysis of Firearm Discharge Residues Using Laser Induced Breakdown Spectroscopy Graduate Theses, Dissertations, and Problem Reports 2019 Chemical Analysis of Firearm Discharge Residues Using Laser Induced Breakdown Spectroscopy Courtney Helen Vander Pyl West Virginia University, [email protected] Follow this and additional works at: https://researchrepository.wvu.edu/etd Recommended Citation Vander Pyl, Courtney Helen, "Chemical Analysis of Firearm Discharge Residues Using Laser Induced Breakdown Spectroscopy" (2019). Graduate Theses, Dissertations, and Problem Reports. 4058. https://researchrepository.wvu.edu/etd/4058 This Thesis is protected by copyright and/or related rights. It has been brought to you by the The Research Repository @ WVU with permission from the rights-holder(s). You are free to use this Thesis in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you must obtain permission from the rights-holder(s) directly, unless additional rights are indicated by a Creative Commons license in the record and/ or on the work itself. This Thesis has been accepted for inclusion in WVU Graduate Theses, Dissertations, and Problem Reports collection by an authorized administrator of The Research Repository @ WVU. For more information, please contact [email protected]. Chemical Analysis of Firearm Discharge Residues Using Laser Induced Breakdown Spectroscopy Courtney H. Vander Pyl Thesis submitted to the Eberly College of Arts and Sciences at West Virginia University in partial fulfillment of the requirements for the degree of Master of Science in Forensic and Investigative Sciences Tatiana Trejos, Ph.D., Chair Keith Morris, Ph.D. Luis Arroyo, Ph.D. Casey Jelsema, Ph.D. Department of Forensic and Investigative Sciences Morgantown, West Virginia 2019 Keywords: Firearm discharge residues, Gunshot residue, Laser Induced Breakdown Spectroscopy, Distance determination, Forensics Copyright 2019 Courtney Vander Pyl ABSTRACT Chemical Analysis of Firearm Discharge Residues Using Laser Induced Breakdown Spectroscopy Courtney Vander Pyl According to the Gun Violence Archive, in 2017, firearms were involved in 57,134 criminal incidents in the United States. The detection of firearm discharge residues (FDR), including inorganic and organic gunshot residues, can provide essential information in such investigations. For instance, when the question of suicide or murder arises, estimating the barrel to victim distance plays a critical role in the outcome of the case. In addition, clothing, wounds and other target materials are often inspected to determine if a bullet has produced an entry or exit orifice. Currently, the most common method for distance determination and identification of bullet entrance holes is by chemical colorimetric tests that react in the presence of nitrites or lead. Although these color tests are widely used in forensic laboratories, the major pitfall is their variability and poor selectivity for gunshot residues. Dark or bloody items significantly diminish the efficacy of these assays, they are difficult to perform on non-movable or large objects, and false positives can be derived from oil, dirt, and other common contaminants. The chance of outside sources affecting the color distribution pattern has led to the exploration of alternative instrumental methods for estimating a shooting distance, including Atomic Absorption Spectroscopy (AAS), Fourier Transform Infrared Spectroscopy (FTIR), X-ray fluorescence (XRF), and Atomic Force Microscopy (AFM). Nevertheless, these instrumental methods have limitations for GSR analysis, as well, such as destruction of the sample, long time of analysis, or complex sample preparation. Therefore, there is a critical need for the development of an analytical method that is sensitive to GSR, fast, practical, non-invasive, objective, and accurate. The primary goal of this study was to investigate the capabilities of LIBS for shooting distance determination and identification of FDR on substrates of interest. The central hypothesis of this research was that Laser-Induced Breakdown Spectroscopy would improve the scientific reliability of the detection and observation of gunshot residues. This assumption was based on the ability of LIBS to perform simultaneous multi-elemental detection at low ppm levels, LIBS’ superior selectivity, and the potential for confirmation of numerous emission species per analyte. To assess the forensic utility of LIBS, the method was developed and validated for the analysis of substrates commonly found during firearm-related crimes. Residues from different ammunitions and firearms were analyzed off 133 fabrics, glass, drywall, and wooden samples. Statistical methods, like principal component analysis and multivariate discriminant analysis were performed to estimate shooting distances and identify the presence of GSR residues. Color tests lead to misclassification of 9 out of 35 unknown shooting distances (26%), while the LIBS method correctly classified 100% of the unknown distance testing samples by Discriminant Analysis. Additionally, LIBS was able to correctly identify elemental profiles of gunshot residues from all standard ammunitions deposited on clothing, drywall, glass, and wood. LIBS allowed for rapid and accurate chemical mapping of GSR patterns on pieces of evidence typically found at a crime scene. Chemical imaging of lead, barium, and antimony provided more objective approaches to estimation of shooting distance and bullet hole identification, compared to color tests. Moreover, LIBS provided enhanced detection of standard ammunitions and partial detection of lead-free ammunitions. However, some challenges still exist with accurate detection and identification of non-toxic ammunitions. The proposed method is anticipated to aid in crime scene reconstruction of criminal events involving firearms. The superior capabilities of LIBS analysis, compared to current practice, increases the certainty on these examinations and enhances the reliability of the information used during the investigative stages and when the evidence is presented in a court of law. ACKNOWLEDGEMENTS First, I would like to express my overwhelming gratitude to my research advisor and committee chair, Dr. Tatiana Trejos, for her mentorship and guidance over the last two years. None of this would have been possible without her support, reassurance, and encouragement. I would like to thank my committee members Dr. Keith Morris, Dr. Luis Arroyo, and Dr. Casey Jelsema for providing thoughtful insight and advice throughout the process. I would also like to thank my fellow graduate and undergraduate research group members who have greatly helped me. Especially Korina Menking-Hoggatt who always listened to my struggles, shared in my frustration of uncooperative instruments, and celebrated all the little achievements with me. Finally, I would like to thank my parents, my sister Chelsea, my boyfriend Cameron, and all of my friends for their endless encouragement and love throughout this whole experience. Thank you for always believing in me. iv TABLE OF CONTENTS ABSTRACT ................................................................................................................................... ii ACKNOWLEDGEMENTS ........................................................................................................ iv LIST OF FIGURES ................................................................................................................... viii LIST OF TABLES ....................................................................................................................... xi 1. LITERATURE REVIEW ........................................................................................................ 1 1.1. Firearm Discharge Residues and Gunshot Residues ............................................................... 1 1.2. Scanning Electron Microscopy-Energy Dispersive Spectroscopy Analysis ........................... 3 1.3. Physical Examination and Colorimetric Tests for FDR Detection .......................................... 6 1.4. Modified Griess Test................................................................................................................ 7 1.5. Sodium Rhodizonate Test ........................................................................................................ 9 1.6. Dithiooxide Test..................................................................................................................... 10 1.7. Current Challenges and Advances on GSR Detection ........................................................... 11 1.8. Laser Induced Breakdown Spectroscopy ............................................................................... 17 2. OBJECTIVES OF OVERALL PROJECT .......................................................................... 22 3. CHAPTER 1: THE DEVELOPMENT, OPTIMIZATION, AND VALIDATION OF LIBS FOR SHOOTING DISTANCE DETERMINATION ................................................... 24 3.1. Overview of Project ............................................................................................................... 24 3.2. Spectrochemical Mapping Using Laser Induced Breakdown Spectroscopy as a More Objective Approach to Shooting Distance Determination ............................................................ 25 3.2.1. Methods and Materials .................................................................................................. 26 3.2.1.1. Firearms and Ammunitions.................................................................................
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