The author(s) shown below used Federal funds provided by the U.S. Department of Justice and prepared the following final report: Document Title: Use of Scanning Electron Microscopy/Energy Dispersive Spectroscopy (SEM/EDS) Methods for the Analysis of Small Particles Adhering to Carpet Fiber Surfaces as a Means to Test Associations of Trace Evidence in a Way that is Independent of Manufactured Characteristics Author: David A. Stoney, Ph.D., Paul L. Stoney, MBA Document No.: 239051 Date Received: July 2012 Award Number: 2010-DN-BX-K244 This report has not been published by the U.S. Department of Justice. To provide better customer service, NCJRS has made this Federally- funded grant final report available electronically in addition to traditional paper copies. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. Department of Justice. Use of Scanning Electron Microscopy / Energy Dispersive Spectroscopy (SEM/EDS) Methods for the Analysis of Small Particles Adhering to Carpet Fiber Surfaces as a Means to Test Associations of Trace Evidence in a Way that is Independent of Manufactured Characteristics Award 2010-DN-BX-K244 David A. Stoney, Ph.D. and Paul L. Stoney, MBA Stoney Forensic, Inc. 14101-G Willard Road Chantilly, VA 20151 This document is a research report submitted to the U.S. Department of Justice. This report has not been published by the Department. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. Department of Justice. Technical Report 2010-DN-BX-K244 Small Particles on Fibers to Test Association Abstract Very small particles (VSP) are ubiquitous in our environment and are virtually ignored by forensic science. These particles range in size from an order of magnitude smaller than conventional trace evidence, down to the molecular level (now routinely exploited through DNA analysis). We move about in a soup that is a combination of VSP that provides an extraordinary, largely untapped resource for forensic associations and source attribution. This project was an initial, highly successful effort to exploit VSP for one specific application. An innovative instrumental trace evidence analysis approach was developed and tested for the recovery and quantitative SEM/EDS analysis of VSP adhering to the surfaces of carpet fibers – one of the most common types of trace evidence examined in crime laboratories. Program goals were: (1) to develop methods to quantitatively remove VSP from carpet fibers and prepare them for SEM/EDS analysis, and (2) to exploit existing computer-assisted SEM/EDS methods to test whether the resulting VSP profiles are useful to quantitatively associate shed fibers with a source carpet. Specific program objectives were to: − Develop suitable methods as described − Use these methods to determine VSP profiles within source carpets − Analyze VSP adhering to single fibers from the source carpets, and determine if their VSP profiles were consistent with an unbiased statistical sampling from the source carpet − Explore between-item variation for VSP profiles using a broader qualitative survey of carpets Appropriate methods were developed and used to assess within-carpet variability using VSP from three different areas on each of nine carpets. Carpet area VSP profiles were defined by a set of ten carpet fibers and the profiles of individual fibers from these areas were compared. Between-item variation was explored using a survey of VSP profiles on an additional 12 carpets. Program goals and objectives were met. The regular occurrence of hundreds to thousands of VSP on individual carpet fibers was demonstrated. The quantity and character of VSP was sufficient to associate fibers with their carpet area of origin. The hypothesis of a strictly quantitative relationship among VSP, as measured using environmental particle profiles, was strongly rejected. These environmental particle profiles were found to be unsuitable to assess VSP variability. An alternative method was developed based on Target Particle Types (TPTs) defined by their elemental profiles as measured by computer-assisted SEM/EDS. Within-carpet and between-carpet variations showed a roughly even distribution for most TPTs and between-carpet variations showed a wide range in types and quantities of VSP. The usefulness of VSP to link of carpet fiber evidence has been established. There is now a clearly achievable potential to use VSP for independent, quantitative testing of the common origin of carpet fibers. To unlock this potential, a set of follow-on research steps have been outlined and are ready to be undertaken. The specific application of VSP to carpet fibers is ready for development, but the proof of principle resulting from this research is of much broader significance for the future of trace Page 2 of 76 This document is a research report submitted to the U.S. Department of Justice. This report has not been published by the Department. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. Department of Justice. Technical Report 2010-DN-BX-K244 Small Particles on Fibers to Test Association evidence analysis. It is a breakthrough providing the impetus and direction for a fundamental change in the way that forensic trace evidence is conceptualized, analyzed and used in the criminal justice system. The results of this research are likely extendable, with minor modifications, to other trace evidence types, and are expected to contribute significantly for those types of trace evidence that have long been considered of low evidential value. Furthermore, entirely new approaches to trace evidence are enabled by exploiting VSP profiles, such as comparing different types of trace evidence with one another and comparing VSP defined by crime scene or suspect environments to that on virtually any item of physical evidence. Page 3 of 76 This document is a research report submitted to the U.S. Department of Justice. This report has not been published by the Department. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. Department of Justice. Technical Report 2010-DN-BX-K244 Small Particles on Fibers to Test Association Table of Contents Abstract 2 Table of Contents 4 Executive Summary 5 I. Introduction 13 II. Methods A. Carpet Sample Selection 16 B. Sampling of Fibers from Carpets 17 C. SEM Imaging and Qualitative Assessment of Particle Abundance on Fiber Surfaces 20 D. Isolation of Particles from Fibers (Protocol Development) 20 E. Isolation of Particles from Fibers (Finalized Method) 21 F. Computer-Assisted SEM/EDS Analysis of Particles 22 G. Analysis of Environmental Particle Groupings 24 H. Within-Sample Elemental Profile Classes 25 I. Selection, Definition and Frequency of Target Particle Types 25 III. Results A. Isolation of Particles from Fibers 26 B. Computer-Assisted SEM/EDS Analyses 27 C. Statistical Testing of Environmental Particle Groupings 33 D. Elemental Profile Groupings and Classes 33 E. Definition of Target Particle Types 33 F. Occurrence of Target Particle Types for Carpets, Carpet Fibers and Process Blanks 37 G. Variation Among Different Areas of the Same Carpet 42 H. Variation Within Single Carpet Areas 49 I. Variation Among Different Carpets 56 IV. Conclusions A. Discussion of Findings 59 B. Discussion of the Underlying Technology and Scope 66 C. Implications for Policy and Practice 67 D. Implications for Further Research 69 V. References 73 VI. Dissemination of Research Findings 76 Page 4 of 76 This document is a research report submitted to the U.S. Department of Justice. This report has not been published by the Department. Opinions or points of view expressed are those of the author(s) and do not necessarily reflect the official position or policies of the U.S. Department of Justice. Technical Report 2010-DN-BX-K244 Small Particles on Fibers to Test Association Executive Summary Our research has demonstrated that hundreds to thousands of very small particles (VSP) cling to the surfaces of individual carpet fibers. We have developed methods to remove these particles, analyze them, and use them to link the fibers to the carpet from which they came. This project focused on one specific trace evidence application (carpet fibers) and one specific instrumental particle analysis method (computer-assisted SEM/EDS) to explore and test a fundamentally different approach to trace evidence analysis. In doing so, a set of reasonable assumptions and choices were made that can themselves be tested and refined for this specific application. As proof of principle our findings are a highly significant breakthrough for the future of trace evidence analysis. They demonstrate a way to remove fundamental limitations of class associations and provide the impetus and direction for fundamental change in the way forensic trace evidence is conceptualized, analyzed and used in the criminal justice system. Further research is encouraged to allow the independent, quantitative testing of common origin using populations of VSP. Problem and Purpose There is a fundamental limitation to the probative value of many of the most common types of trace evidence (e.g., fibers, glass, paint) because their characteristics are determined by their manufacture. As mass-produced commodities, probative value is limited to class associations. Multiple-transfer cases shatter this limitation. These are cases where a set of different trace evidence materials, found on a suspect, correspond to sources at a crime scene, and/or the reverse: where a set of trace evidence materials, found at the crime scene, correspond to suspect- related sources. The well-known case of Atlanta child murders provides an excellent example, where fibers corresponding to the trunk of Wayne Williams’ car, his bedroom carpet, his bedspread, and his blanket were all found together on multiple victims.