options that allow laboratories to substitute a concatenation of simple methods if they do not have access to the preferred analytical equipment (e.g., GC-MS). It is questionable, however, whether all of the possible combinations recommended by SWGDRUG would be acceptable in a scientific sense, if one’s goal were to identify and classify a completely unknown substance. The committee has been told that experienced forensic chemists and good forensic laboratories understand which tests (or combinations of tests) provide adequate reliability, but the SWGDRUG recommendations do not ensure that these tests will be used. This ambiguity would be a less significant issue if the reports presented in court contained sufficient detail about the methods of analysis.
Fingerprints, palm prints, and sole prints have been used to identify people for more than a century in the United States. Collectively, the analysis of these prints is known as “friction ridge analysis,” which consists of experience-based comparisons of the impressions left by the ridge structures of volar (hands and feet) surfaces. Friction ridge analysis is an example of what the forensic science community uses as a method for assessing “individualization”—the conclusion that a piece of evidence (here, a pattern left by friction ridges) comes from a single unambiguous source. Friction ridge analysis shares similarities with other experience-based methods of pattern recognition, such as those for footwear and tire impressions, toolmarks, and handwriting analysis, all of which are discussed separately below.
Friction ridge analysis is performed in various settings, including accredited crime laboratories and nonaccredited facilities. Nonaccredited facilities may be crime laboratories, police “identification units,” or private practice (consultants). In some instances, the latent print examiner is employed solely to perform latent print casework. Some examiners may also perform other types of forensic casework (e.g., footwear and tire impressions, firearms analysis). In some agencies, fingerprint examiners also are required to respond to crime scenes and can be sworn officers who also perform police officer/detective duties.
The training of personnel to perform latent print identifications varies from agency to agency. Agencies may have a formalized training program, may use an informal mentoring process, or may send new examiners to a one- to two-week course. The International Association for Identification (IAI) offers a training publication, “Friction Ridge Skin Identification Training Manual,”17 and the Scientific Working Group on Friction Ridge
International Association for Identification. Friction Ridge Skin Identification Training Manual. Available at www.theiai.org.