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2. Reference Documents
3. TerminologyClass is a group of items that share properties or characteristics. 4. Summary of GuidelineThe other Scientific Working Group for Materials Analysis documents
in this issue address the principal methods of forensic glass comparisons
in the order that they should be performed, if practicable. The
various analytical methods available for glass analysis yield different
kinds of information. It is highly desirable to select a combination
of methods and apply them in an order that provides the most useful
information, while most effectively using the laboratory's resources.
5. Significance and Use
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5.1. | The other Scientific Working Group for Materials Analysis documents in this issue are designed to assist the forensic glass examiner in selecting and organizing an analytical scheme for locating, collecting, identifying, and comparing glass. The size and condition of the samples, as well as the information requested will influence the selected analytical scheme. |
5.2. | Glass is a material commonly found in our environment. The breakage characteristics of glass under impact forces can produce features that can be used as physical evidence in many types of cases. The various examination techniques described in the other Scientific Working Group for Materials Analysis documents in this issue apply to most types of glass, including the following: flat glass used for windows, doors, display cases, and mirrors; container glass; tableware glass; optical glass; decorative glass; and specialty glass used for headlamps, cookware, and others. |
5.3. | Typically, forensic glass examinations involve a comparison of samples from known and questioned sources to determine if they originated from different sources (e.g., window from a suspect's car compared to glass recovered from the victim's clothing). This comparison involves the recognition and evaluation of class characteristics that associate materials to a group but never to a single source. Conversely, individual characteristics allow the association between two or more items with each other to the exclusion of all other items. For glass examiners, this can only occur when pieces of glass are physically matched. |
5.4. | Due to inherent heterogeneity of physical and chemical properties within a single source of glass, it is essential to emphasize the need to collect and analyze a sample(s) of the known source for comparison to any recovered fragments. |
Proper sample handling and preparation techniques are prerequisites for obtaining reliable results. See the Scientific Working Group for Materials Analysis Collection, Handling, and Identification of Glass.
See the other Scientific Working Group for Materials Analysis documents in this issue for specific analysis information.
See the other Scientific Working Group for Materials Analysis documents in this issue for general report considerations.
Caddy, B. Forensic Examination of Glass and Paint, Taylor
and Francis Forensic Science Series, London, 2001.
Koons, R. D., Buscaglia, J., Bottrell, M., and Miller, E. T. Forensic
glass comparisons. In: Forensic Science Handbook. 2nd
ed. R. Saferstein, ed. Prentice-Hall, Upper Saddle River, New Jersey,
2002, Volume I, pp. 161-213.