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1.1 This guide covers the forensic physical fit examinations for the macroscopical and microscopical examinations of broken, torn, or separated materials for the purpose of determining whether or not they were once joined together to form a single object. This guide is intended as an overview of the process for the physical fit examination of these materials and to assist individuals in the evaluation and documentation of their physical comparisons.

1.2 This standard is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic casework.

1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

5.1 This guide can assist the examiner in selecting and organizing a general analytical scheme for the evaluation and documentation of physical comparisons of materials for a potential physical fit. The type and size of material influences the exact steps and equipment needed to assess the physical fit. Evaluation, documentation, and interpretation are all important parts of a physical fit examination.

5.2 This guide addresses special considerations for physical fit analysis for glass, skeletal material, polymers, tapes and textiles.

5.3 Foundations of physical fit examination in forensic science are described in the literature, including studies on the fractography of different materials and the use of physical fit examinations in forensic casework (1-12).

5.4 It is not the intention of this guide to present comprehensive theories regarding the mechanism of fractures, tearing, cutting, or other methods of separation. This information is available from training courses and reference materials such as Practice C1256 and others (3-7, 13).