Trace Evidence Symposium 2011: Science, Significance and Impact

The Homemade Explosive Workshop will describe the chemistry behind the formulation of improvised explosive materials. Additionally, the common sources of the components of these homemade explosives both domestically and internationally will be illustrated with case studies and intelligence data developed from numerous incidents.

This one‐day workshop comprises three parts: Color Perception and Chemistry; Conventional and New Fiber Technologies; and New Approaches to the Analysis of Dyed Fibers. The goal of the workshop is to highlight key issues of color in the courtroom; review the chemistry of dyes, pigments, and synthetic and natural fibers; introduce new technologies in textiles of relevance to forensic science; and discuss state‐of‐the‐art methods of dyed fiber analysis, especially liquid chromatography time‐of‐flight mass spectrometry and time‐of‐flight secondary ion mass spectrometry.

The purpose of this workshop is to teach the basic, practical technique for identifying the essential soil‐forming minerals using the polarizing microscope. Certain combinations of specific morphological and optical properties can be used to characterize most mineral species or families (groups). By the end of the day, students will have learned to identify the most frequently encountered soil‐forming minerals. The importance of single grain isolation for analysis by SEM/EDS and Raman microprobe for identifying difficult grains will also be discussed.

This workshop aims to show how the mechanism of fiber transfer in case of contact traces works, what the examiner has to consider, what kind of persistence ability we have to expect and what potential fiber traces can offer in forensics. The workshop will cover the collection of trace evidence (fibers) at the crime scene and the aspects and considerations of where to collect evidence on the scene. The problem of contamination and sensible solutions will be discussed and shown during this workshop. The workshop will cover different techniques and schemes of trace recovery and various materials used for this purpose. Another big issue addressed by this workshop will be the difference between fiber behavior on moved and unmoved objects or victims and also moving victims and offenders. The behavior and distribution on different surfaces will be assessed, and persistence studies will be presented (persistence of fibers on skin, clothes) and evaluated during practical exercises including the aspects of transfer (primary, secondary), loss and possible redistribution of fibers.

This one‐day workshop will review the application of statistical methods to practical decisionmaking requirements in the forensic laboratory. Of particular interest is the application of statistical methods to the analysis of both univariate and multivariate data based on class evidence, where the challenge is to assess similarity or dissimilarity in comparisons of questioned and known samples. The specific statistical concepts to be covered include measures of accuracy and uncertainty, confidence intervals for means, hypothesis tests (both parametric and nonparametric) for comparing means and for comparing variances, one‐way analysis of variance, and outlier detection. The use of receiver‐operator characteristic (ROC) plots for evaluating decisions will also be presented, as will the application of multivariate statistics to trace evidence data from a variety of spectroscopic (e.g., UV/visible, IR, and Raman spectra), chromatographic, mass spectrometric, and other sources. Principal component analysis, linear discriminant analysis, and cluster analysis for comparison and discrimination of trace evidence data will be presented, along with necessary validation procedures and multivariate hypothesis tests.

This workshop will outline the techniques that are commonly used for the identification of chemical unknowns. Specific attention will be paid to microscopial examinations, wet chemical techniques, and various forms of instrumental analysis. A logical approach to the examination of chemical unknowns will also be discussed. As part of the workshop, several attendees will be invited to participate. These individuals will receive a set of blind samples to be analyzed in their laboratories using their protocols. The results obtained and the methods used during analysis will be discussed.

Over 30 years ago, the Royal Canadian Mounted Police (RCMP) created an automotive paint database to help forensic scientists determine vehicle manufacturer, make, assembly plant, and year from a small paint chip left at a crime scene. This database, now known as Paint Data Query (PDQ), has grown to include samples of vehicle paint not only from North America, but also from Australia/New Zealand, Japan, and Europe. The PDQ workshop is designed to be a hands‐on training session in which the attendees will receive instruction in the organization of the database, will practice classifying paint systems, will enter queries into PDQ, and will gain the basic interpretive skills necessary for evaluating the results obtained from a search. With an understanding of the database software and confidence in the query parameters entered, the paint examiner will be able to provide an accurate assessment of possible sources for a questioned paint sample, utilize the database for making significant assessments for paints in K/Q comparative situations, and utilize the database for maintaining their understanding of the structure and chemistry of modern automotive paints. Prior training and practical experience in paint analysis and FTIR paint examinations and classifications are recommended.

The Advanced Fire Debris Workshop will include discussion on the following topics: environmental degradation, competitive absorption complications, petroleum refining and fuel variations, E1618 new report writing section, and Molotov cocktail study. There will also be a group participation with regard to difficult fire debris cases.

After attending the workshop, attendees will have learned basic theory of fracture match and gained a better understanding of the applications of this examination in forensic casework. Attendees will have the opportunity to apply their skills by working on practical exercises utilizing case scenarios designed to challenge them and refine their ability to apply this technique. This presentation will impact the forensic community by providing attendees knowledge of fracture match examinations and its uses in the forensic science/law enforcement community.

The goal of this 4‐hour workshop is to familiarize participants with procedures for sampling, preparing, and examining animal hair using transmitted light microscopy. Activities will include a review of mammalian taxonomy and the types of forensic cases involving animal hair; examination and sampling of pelts; preparation and curation of hair standards and exemplars; and use of transmitted light microscopy to examine medullary and cuticular characteristics, particularly in domesticated mammals.

This workshop will familiarize participants with the microscopical identification of various types of natural fibers, including vegetable fibers, wool‐type fibers, silks and mineral fibers, which may be encountered in criminal investigations. Lectures will focus on the examination of microscopical structures used for the recognition of various natural fiber types. There will also be a review of natural fiber sources, processing, and end uses.

This half‐day workshop is designed to introduce new and non‐practitioners to the various subdisciplines of trace evidence. Specific discussions on the background, analysis, and significance of paint, hairs, fibers, and glass as evidence will be provided. In addition to these core trace subdisciplines, similar information will be provided on the benefits and caveats of lubricant analysis in cases of sexual assault, and an overview of non‐traditional trace evidence will also be provided. Who should attend? The information provided will serve to augment the training of those who are new to the field and provide a strong overview to those who are unaware of the benefits that trace evidence examinations possess.

The aim of this opening panel is to discuss the current challenges, concerns and successes in trace evidence practice in order to set the tone for the rest of the meeting and, in particular, to provide background for the next panel. The presentations will stimulate an honest debate and describe the issues already raised by NAS and others with an aim towards laying the foundation for making continued progress in our discipline.

The panel will discuss how trace evidence is moving forward in various aspects of this unique field. Participants will receive perspectives from the international, federal and state communities. This panel will also discuss specific topics proposed to them or potential comments raised in the debate/panel before the session. The session will end with questions from the attendees.

The presenters in this session will discuss various approaches to forensic soil analysis and the current state of this type of testing within the United States. The time at the end of the session will be devoted to questions and answers or a panel and audience discussion on soil analysis.

This session will include presentations regarding the analyses and identification of pigments encountered in paint, the discriminating power of physical and chemical comparisons of singlelayer white architectural paints and an overview of the Paint Data Query (PDQ) database.

This panel will deal with a variety of trace evidence materials dealing with analytical techniques for explosive, airbag residues, gunshot residues and tire treads examinations.

The presenters in this session will discuss different approaches to the interpretation, evaluation, and techniques utilized for elemental analysis of glass for forensic casework.

This session will focus on new advances in the analysis of dyed fibers. Presentations will be on topics of discrimination of fiber trace evidence via dichroic ratio measurements, UV-visible microspectrophotometry, time-of-flight mass spectrometry in conjunction with capillary electrophoresis or liquid chromatography, statistics and fibers comparisons, and assessment of automotive fibers.

The presenters in this session will discuss analytical techniques used on a variety of different trace evidence materials including condom and sexual lubricants, black electrical tape, glitter, non-human DNA, and polyurethane foam particles. Two cases involving unusual trace evidence will also be presented.

One of the unique responsibilities of the trace evidence examiners at the Tarrant County (Texas) Medical Examiner’s Office is the processing of decedent’s bodies for evidentiary materials. Last year alone, the trace evidence team examined approximately fifty bodies. This presentation will outline the procedure utilized to efficiently and effectively recover trace materials in a morgue setting prior to autopsy. Numerous case examples will be related to demonstrate the value of this procedure.

This session will include presentations on the use of instrumentation for the micro analysis of trace evidence including the use of SERS (Raman) methods for dye analysis, the use of a combined Raman/LIBS microscope system, the use of a femtosecond laser ablation system coupled to ICP‐MS and a comparison between various instrumental methods for the characterization of glass evidence.

Trace evidence reporting has been under scrutiny since the NAS report. The question is, how to assess the significance of our findings? This panel will explore different approaches to interpreting trace evidence data.

(Keynote Lunch Presentation) In recent years trace evidence has become, almost exclusively, a tool to be used at trial. Its traditional use, however, was to help detectives in developing leads to further their investigations. This presentation will first describe a few historical cases that originally highlighted the value of microscopic trace evidence in solving crimes and will be followed by several examples from the author’s casebook that illustrate the success of this approach in recent investigations. The principles underlying this approach and the techniques and thought processes that lead to its successful application will be described and illustrated.

This session will discuss the various report writing formats currently in use in the Trace Evidence community. The use of levels of association versus reporting the results and saving a detailed discussion of the methods and interpretation for court or including a description of methods and interpretation into report documents will be covered as well as how these formats have been received in the criminal justice community.